September 20, 2009I've been having a hard time figuring this problem out. While driving between 40-50 MPH and the RPM's are about 1200, the trucks "bucks" - a real strong jerking motion, as if it wants to shifts. It happens when there is a bit of an upgrade. If I get the RPM up to about 1800+, it stops. I'm not sure if it is the engine or transmission.
I had the transmission fluid changed (@ 60K), fuel filter changed, cleaned the fuel injectors, cleaned the air filter, but no change. I also had it checked out at the dealer thinking the shift timing was off, but they did not find any error codes.