Date: 202105
Local time of day: 0601-1200
Location: ZZZ.Tower, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737 MAX Series Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach; Takeoff / Launch
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Autothrottle/Speed Control
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Communication Breakdown
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Executed Go Around / Missed Approach; Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Human Factors; Software and Automation; Aircraft
Primary problem: Aircraft

Narrative: During TO out of ZZZ thrust levers anomaly- TO thrust setting as I remember was 84.6; however; when First Officer selected TOGA the thrust increased to over 90% N1 before reducing. Discussed with First Officer after climb out after verifying First Officer had as I expected acted properly (setting thrust) continued to ZZZ1. Executed the visual approach to Runway XX at less than 50 feet thrust lever(auto throttle) anomaly - executed go around. ATC cleared us to 2;000 - during the Go Around I feel it's safe to say we were in the yellow and mitigating any transition into the red by both actively flying/monitoring aircraft instrumentation and following SOPs and yes very deliberately. There was a surprise effect from the aircraft not acting as directed (thrust levers/ auto throttle) as the approach itself was stable. Then we were vectored in visual conditions back around for a second approach to Runway 31. After parking at the gate in ZZZ1 Maintenance was notified of the irregularities with thrust levers (auto throttle).The aircraft was removed from service by Maintenance.Thrust lever / auto throttle anomaly that added a startle effect and divided attention or required additional attention. We could have after the missed approach disconnected the A/T but felt better about closely monitoring/ guarding the thrust levers.


Second narrative: On the take off from ZZZ when I pressed the TOGA button; the throttles rapidly advanced to near full forward; and then slowly retarded to the selected takeoff thrust as we were rolling down the runway.  The throttles came forward very rapidly and went further forward then I would expect.  We were set for a 22K takeoff with an assumed temperature reduction. After takeoff the Captain and I discussed the anomaly.  It was very unusual. The rest of the flight; up to the landing flare; was normal.  I was flying the new visual approach. The approach was loaded into the FMS. The autopilot was engaged. I think I remember disengaging the autopilot if the final turn to final.  In the flare; below 50 feet the throttles began to advance by themselves. I remember being right on speed prior to this. I felt the throttles move forward; and I remember trying to hold them back.  I think the autothrottles were attempting to go around.  I felt the aircraft 'ballooning' and I saw that I was now going to fast (I remember seeing 155 knots). At this point I said go around and pressed the go around button. We climbed out and tower gave us a visual downwind to return. The go around was a normal go around. After cleaning up; I went right back to flaps 1 for the downwind. I was trying to process what just happened and the Captain and I discussed it. We were both surprised by the auto throttle. While turning base; the auto throttles were doing a poor job of holding command bug. They were very slow to respond. I turned off my flight director and visually flew a visual pattern (I had no lateral guidance from the FMS; the approach had not been resequenced. I know the airport very well could see where I needed to go.  I left the auto throttles engaged but I had a firm hand on the throttles. While on base; the air speed got 5 knots slow and I manually pushed the throttles up to speed up. I completed a visual approach and normal flaps 40 landing with flight director off and auto throttles engaged. The auto throttles functioned normal after I had manually pushed them up; but in retrospect I should have disconnected them and flown manually. They were definitely suspect at this point. The flaps 40 approach and landing was normal and smooth. The auto throttles worked as they should.  We had a mechanic at ZZZ1 meet us and we wrote up what had happened. The next morning while eating breakfast; I was 'bothered' by what had happened and I called Name to discuss the anomaly.  We discussed the anomaly in detail. He didn't have any answers either; but said he would keep an eye on the aircraft; X. Additional note; the approach was stable prior to the auto throttle anomaly. We were following an [aircraft] that was going very slow. We were minimal space behind them so we were right on speed throughout the approach to flare. I believe the autopilot was engaged until the turn to final.I am not sure if this was a fault with the airplane auto throttle; a 737 Max anomaly or a coding issue with the new visual approach? Thinking about what had happened on the takeoff; I suspect something was wrong with the auto throttles. I am fairly new to the Max. [No suggestions]; however in retrospect I should have turned off the auto throttles when it became clear they were not working correctly after the go around.


Synopsis: Flight Crew reported auto throttle anomalies on take off and again on landing required a go around.