I have a 2002 Ranger Edge 3.0L v6, with an automatic trans., and it has developed a problem of the rpm fluctuating between 2500 rpm, then will jump up to 3000 rpm, then drop back to 2500, then back & so forth. This happens while driving with & without the cruise control on, mostly highway miles, 30 miles 1 way to work. I have had the transmission fluid changed and a new filter put in, and the mechanic said that everything looked good. This problem seemed to arise after I had to replace the camshaft sensor up by the firewall. Any ideas would be greatly appreciated, this seems to be impacting my fuel consumption as well.

 

The reason the RPM is jumping around is that the transmission is shifting into a lower gear, and then shifting back into the higher gear. The transmission is electronically controlled. Try taking the battery cable off for a night. This will clear the transmission's memory, then when you drive, it will relearn its shift patterns. Might not change anything, but its worth a try.

 

Thanks Riceman, I will give it a shot.

 

Also check your trans fluid. Low fluid can cause this as well. I found out the hard way in my work van.