New guy here. Have a 2007 Honda Fit with 166,000 miles on it. 5 speed automatic transmission. Car runs and looks fabulous, as it very rarely gets driven in the Michigan winters (salty roads).

Anyway, transmission is normal, upshifting and downshifting the way it should, until I get into 5th gear. In 5th gear, going about 55mph with no load to speak of on the engine (level piece of ground), sometimes if feels like it wants to very subtly drop out of "lockup".......like a very slight glitch in the transmission. It only does it around 55mph and when I'm not pressing the engine. Not sure how else to explain it.

Changed the transmission oil a couple times with Honda fluid. New filter.. Didn't make a difference. Possible top gear shift solenoid?