The dryer works great.  However, when it was installed, the installers did not check if the exhaust cross- section was big enough. This issue will not appear as a failure on the installation test. The dryer was consuming 2x as much gas as my 25 y.o. dryer.  After thinking about it a bit, I removed our 47 year old exhaust vent and replaced it with a vent with a much larger cross-section.  Problem fixed.  LG should specify the minimum exhaust  in the installation manual.  I would estimate it to be 3.5-4 inches.