[acme1]

My burb is doing the exact same thing and has been irritating me for months now. I cant seem to pinpoint the problem. The only code I can pull from it is an O2 low voltage on bank 1 & 2 sensor 1 and after clearing the codes the only way they come back is under heavy acceleration or when I am climbing a steep hill. I know the O2 sensors have alot to do with the ECM and drivetrain switching them into safe mode when there are any problems. This triggers the transmission to stay in third (AAMCO told me this) in order to get you home. Other than that the truck runs great except for the symptoms you posted about and the fact that I cant climb any steep hills without an almost complete loss of power and major shaking. Sorry I couldn't be that helpful on the cause of your problem but if you do find the solution to it PLEASE post back so I know what to do with mine.