I've seen only a few post about this problem and ive yet to really find an answer. I have a 2001 24v and when I get to around the 35 to 45 Mph range and once my rpm settle at about 1200 to 1400, the rpm will jump back and forth between 1200 and 1400. You can hear the engine jumping rpms and the whole truck jerks with the rpm jump. If I let off the pedal it will stop, or I get irritated and floor it until
it stops. This has been going on for about 3 months

 

Auto or manual

 

automatic and I fixed it this morning, I read that it was an electrical problem from the alternator wire creating I guess white noise and it was messing with the tranny when it was looking for forth gear it can be solved by wrapping the wire in tin foil. I did not do this, I used some left over amp power wire 4g and ran it directly from the alternator to the battery and it worked perfectly