RPM problems

My truck has been having some issues. 2001 Dodge Ram 1500 4x4. While driving down the road the rpms jump. Seems worse when the cruise is turned on & it also seems to do it when I hit bumps. Lately it has become much worse. When I start the truck it idles real high then drops some, then idles back up around the 2000 mark & drops again, etc, etc.. My check engine light has been on & when I took it to Advanced to put the handheld on it, all it said was my gas cap was loose. He tightened it & the light went out until I got gas again & it came back on. Which I then tightened the living hell out of it & the light would not go off this time. Does this sound like a vacuum problem? Should I try a new gas cap? I just put new plugs in the truck a couple months ago. Change the oil regularly & just checked & filled the tranny fluid, it was a bit low.

Any help would be a ppreciated.

Thanks,
Dan

 

*Bump*

Anyone have any ideas?

 

*Bump again*

After $58, I can rule out the Idle Air Control Valve. It did fix the idle RPM problem, idles much nicer now, but I still get the RPM jumps when I hit bumpes in the road.

Was going to try feul filter next, mainly because it's cheap & it hasn;t had one probably since new. I know I never put one on in the past 4 years.

Anyone have any other ideas yet?

Thanks,
Dan

 

What is the transmission doing when you get the rpm spikes?

 

I'm not sure about what engine you have, but might be throttle position sensor (if it has one) going goofy. Also sounds like a loose wire somewhere that makes and breaks contact with vibration (bumps in the road). I'd go over all obvious wire connections especially those related to ignition/fuel delivery. I doubt it is the fuel filter as I would think it would run poorly all the time.

 

Any quick cahnge when you hit bumps suggests to me, as above, that there is a loose wire somewhere.
Also as suggested above, if the TCC(torque converter clutch) is locked up at highway speeds(as it should be above 45), if the engine speeds up, everything should speed up. If not, the trans may be slipping, but that would indicate more than one problem.

 

Thanks for the suggestions guys, but Bob22 gets the grand prize, it was the Throttle Position Sensor.

Dan

 

Glad i'ts fixed!

 

Glad the guess was useful; especially glad it wasn't the O2 sensor that everyone thinks is the cause of all problems and hardly ever is.