[T-Mobile myTouch 4G Slide] Blue6IX:
Here is the build.prop file put together by Undeadk9 way back when that solved the other half of the GPS issue:

ro.ril.enable.a53=1
ro.ril.enable.dtm=0
ro.ril.gprsclass=10
ro.ril.hsdpa.category=10
ro.ril.hsupa.category=6
ro.ril.hsxpa=3
ro.ril.hep=1
[B]ro.ril.def.agps.mode=1[/B]
ro.ril.fast.dormancy.timeout=10
[B]ro.ril.def.agps.feature=1[/B]
ro.ril.disable.fd.plmn.prefix=23402,23410,23411
ro.ril.enable.sdr=0
ro.ril.enable.gea3=0
ro.ril.enable.amr.wideband=0
ro.ril.rxd.mode.nv=10
ro.ril.bler.threshold.nv=125
ro.ril.rscp.threshold.nv=110
ro.ril.enable.rxd=1
ro.ril.oem.cnap=1
ro.ril.enable.r8fd=1
ro.com.google.clientidbase=android-tmobile-us
ro.com.google.clientidbase.vs=android-hms-tmobile-us
ro.com.google.clientidbase.ms=android-hms-tmobile-us
ro.ril.enable.ganlite=1
ro.product.model=myTouch_4G_Slide

# begin build properties
# autogenerated by buildinfo.sh
ro.aa.rid=108
ro.aa.skulist=531
ro.aa.customizationid=201767
ro.aa.mainsku=531
ro.aa.taskid=201815
ro.aa.romver=1.28.531.9
ro.aa.maincid=T-MOB010
ro.aa.cidlist=T-MOB010
ro.aa.project=Doubleshot
ro.aa.modelid=PG5910000
ro.build.changelist=100058
ro.com.google.clientidbase=android-htc
ro.aa.rid=108
ro.aa.skulist=531
ro.aa.customizationid=201767
ro.aa.mainsku=531
ro.aa.taskid=201815
ro.aa.romver=1.28.531.9
ro.aa.maincid=T-MOB010
ro.aa.cidlist=T-MOB010
ro.aa.project=Doubleshot
ro.aa.modelid=PG5910000
ro.build.changelist=100058
ro.com.google.clientidbase=android-htc
ro.build.id=GRJ22
ro.build.display.id=GRJ22
ro.build.version.incremental=100058
ro.build.version.sdk=10
ro.build.version.codename=REL
ro.build.version.release=2.3.4
ro.build.date=二 7月 5 19:43:46 CST 2011
ro.build.date.utc=1309866226
ro.build.type=user
ro.build.user=undeadk9
ro.build.host=ubuntu
ro.build.tags=release-keys
ro.product.model=HTC Doubleshot
ro.product.brand=tmous
ro.product.name=htc_doubleshot
ro.product.device=doubleshot
ro.product.board=doubleshot
ro.product.cpu.abi=armeabi-v7a
ro.product.cpu.abi2=armeabi
ro.product.manufacturer=HTC
ro.product.locale.language=hdpi
ro.product.locale.region=US
ro.wifi.channels=
ro.board.platform=msm8660
# ro.build.product is obsolete; use ro.product.device
ro.build.product=doubleshot
# Do not try to parse ro.build.description or .fingerprint
ro.build.description=1.28.531.9 CL100058 release-keys
ro.build.description=1.28.531.9 CL100058 release-keys
ro.build.changelist=100058
ro.product.ua=
ro.build.fingerprint=tmous/htc_doubleshot/doubleshot:2.3.4/GRJ22/100058:user/release-keys
ro.build.project=201815
ro.product.version=1.28.531.9
ro.build.languageremove=0
keyguard.no_require_sim=1
# end build properties
#
# system.prop for doubleshot
#

ro.sf.lcd_density=240

debug.fb.rgb565 = 0
#C2D
debug.composition.type = c2d

rild.libpath=/system/lib/libhtc_ril.so
# RilLibPath for Ganlite by Godel_Chen
rild.libpath.ganlite=/system/lib/librilswitch.so
rilswitch.vendorlibpath=/system/lib/libhtc_ril.so
rilswitch.ganlibpath=/system/lib/libganril.so

# Modify MMS APN retry timer from 5s to 2s.
ro.gsm.2nd_data_retry_config = max_retries=3, 2000, 2000, 2000

# RF team request
ro.ril.enable.dtm = 1
ro.ril.gprsclass = 10
ro.ril.hsdpa.category = 10
ro.ril.hsupa.category = 6
ro.ril.hsxpa = 3
ro.ril.hep= 1

# Default network type.
# 0 => WCDMA preferred.
ro.telephony.default_network=0

wifi.interface=eth0
wifi.supplicant_scan_interval=15

# The OpenGL ES API level that is natively supported by this device.
# This is a 16.16 fixed point number
ro.opengles.version = 131072

# This is a high density device with more memory, so larger vm heaps for it.
# Change to 125m, due to 2.3.4 GB already change to 125m
dalvik.vm.heapsize=125m

# For HSDPA low throughput
ro.ril.disable.power.collapse = 1

# For China NEL
ro.ril.enable.prl.recognition = 1

# For emmc phone storage
ro.phone_storage = 0

# For ext4 file system
ro.ext4fs = 1

# For FOTA setting (leave empty value to use default)
ro.htc.checkin.url = http://andchin.htc.com/android/checkin
ro.htc.checkin.crashurl = http://andchin.htc.com/android/crash
ro.htc.checkin.url_CN = http://andchin.htccomm.com.cn/android/checkin
ro.htc.checkin.crashurl_CN = http://andchin.htccomm.com.cn/android/crash
ro.htc.checkin.exmsg.url = http://fotamsg.htc.com/android/extra/
ro.htc.checkin.exmsg.url_CN = http://fotamsg.htccomm.com.cn/android/extra/
ro.htc.appupdate.url = http://apu-chin.htc.com/check-in/rws/and-app/update
ro.htc.appupdate.url_CN = http://apu-chin.htccomm.com.cn/check-in/rws/and-app/update
ro.htc.appupdate.exmsg.url = http://apu-msg.htc.com/extra-msg/rws/and-app/msg
ro.htc.appupdate.exmsg.url_CN = http://apu-msg.htccomm.com.cn/extra-msg/rws/and-app/msg

# Release Bluetooth HW/SW information
ro.bt.chipset	= Broadcom BCM4329-B1
ro.bt.stack	= Broadcom BTL-A
ro.bt.stack.version	= 2.0.50.032
#0x10000010010100100000011 represent bt profile list
ro.bt.profiles	= 4270339

# Properties of BTLA stack
service.brcm.bt.activation = 0
service.brcm.bt.srv_active = 0
service.brcm.bt.hcid_active = 0
service.brcm.bt.btld = 0
service.brcm.bt.btld_pid = 0
service.brcm.bt.avrcp_pass_thru = 0
service.brcm.bt.avrcp_toggle = 1

# For quick boot mode
persist.sys.shutdown.mode = hibernate

# For opensense sdk
ro.htc.common.version = 2.0.0.0

# Properties of Scalado Denoise param.
postprocess.iso_midband = 400
postprocess.denoise_level = 5

# Properties of Burst mode param.
persist.camera.burst.interval = 300

# Following property will be reference by Settings.
ro.product.processor = 1.2 GHz dualcore
ro.product.ram = 768MB
ro.product.display_resolution = 3.7 inch WVGA resolution
ro.product.main_camera = 8M
ro.product.front_camera = VGA
ro.product.bluetooth = 3.0
ro.product.wifi = 802.11 b/g/n

# For opensense sdk
ro.htc.common.version = 3.0.0.0

# Extend key dispatching timeout
keydispatchtimeout = 15000

#
# ADDITIONAL_BUILD_PROPERTIES
#
ro.url.legal=http://www.google.com/intl/%s/mobile/android/basic/phone-legal.html
ro.url.legal.android_privacy=http://www.google.com/intl/%s/mobile/android/basic/privacy.html
ro.com.google.networklocation=1
ro.setupwizard.mode=DISABLED
ro.setupwizard.mode=OPTIONAL
ro.config.ringtone=QuietlyBrilliant.mp3
ro.config.notification_sound=Zeta.mp3
ro.config.alarm_alert=NewDay.mp3
ro.config.cal_notification=Epsilon.mp3
ro.config.msg_notification=Gamma.mp3
ro.setupwizard.mode=DISABLED
ro.com.google.gmsversion=2.3_r4
media.a1026.nsForVoiceRec=0
htc.audio.alt.enable=1
htc.audio.hac.enable=1
ro.setupwizard.enterprise_mode=1
ro.media.codec_priority_thumb=so
dalvik.vm.dexopt-flags=m=y
net.bt.name=Android
dalvik.vm.stack-trace-file=/data/anr/traces.txt

If you are using a ROM that is not Bulletproof, and still suffer GPS issues after flashing the GPS Configuration Fix - you will need to tweak your signal strength to make it work right.

--------

Something else to note:

The stock build.prop also has three issues that I set which you will need to edit:

ro.ril.def.agps.feature=1

ro.ril.def.agps.mode=1

And you will find a third entry that mirrors one of these near the middle-bottom of the file you will have to delete.

Make these changes to the build.prop that I bolded - these were the rest of my contribution to the GPS fix.

You will need to comb through the build.prop to figure out what changes Undeadk9 made and if you need to make them for the ROM you are running.

I am unable to provide much more help then this at this time - I showed you the changes I made and where to look for the changes Undeadk9 made - if you need to fix it further then what i've already done for you... you will have to do it yourself.