Ok, I wish I was smarter about this stuff. The th400 behind my 1990 2wd Suburban feels like it is searching for a lower gear. It doesn't seem to be slipping but the engine revs as it downshifts for no reason. Also seems to be "tripping" into a higher gear. when it shifts into 3rd. Is there any easy fix to pursue or is the tranny just giving out. I just bought the Burb a week ago.