My RPM's are bouncing and I can't figure out why!?

(2011-08-17 14:20:18)

1. Connor Sirovy Says: I have a 2000 Dodge Dakota 4x2 Club Cab with a 4.7 L Magnum v8! While my truck is sitting in an idle the RPM's will bounce between 500 RPM and 2500 RPM, but lately I noticed while on the Hwy going about 55 mph it is starting to bounce between 1500 RPM and 3500 RPM! I took it into the dealership and they tapped on the Throttle Position Sensor (TPS) and they said it stopped! So lately when it happenes I have tried tapping the TPS but it isn't stopping. I have also noticed that it is more severe if it's hotter out or has sat out in the sun for a long period of time. I am from Iowa so if I leave for work early in the morning when it is colder it may not do it or it might do it but not as much as it does mid day after sitting outside in the hot sun while I'm at work. Has anyone else had this problem and figured out what it is or how to fix it? Please help me!

2. Gary Says: You're going to have to replace TPS which Dealer should have done in the first place. Also get intake plenum cleaned and replace fuel filter if not been changed in last 36000 miles.

3. CactiJoe Says: The Throttle Position Sensor is a good guess and the other likely candidate is the fuel pump. Had this occur on a VW GTI and Ford Taurus. When the fuel pressure fluxuates because of a dying fuel pump the RPM's go up and down like clock work. Good Luck!