[detcordram]

So when I start the engine it revs up and down between 1100-1400 for about 20 secs and then drops to about 800-900 for around 45 secs then repeats, It does the same thing if I try idling down the street, Im just trying to stay under the neighborhood speed limit and the neighbors are looking at me like Im trying to show off by revving my engine. From what I've tried looking up myself I think it could be the Idle Air control Valve or throttle position sensor, Both seem to be easy enough to try replacing myself and only $30-$40 at the local autozone, another symptom is if Im in park and have the air running for longer then a few minutes I start getting a hissing sound and the engine goes from a nice purr to almost nothing and then goes back to normal if I start driving. Any ideas of where to start or if its a completely different problem?

 

[RamTech]

Start by verifying I didn't have any vacuum leaks, including the one that can be created by a blown plenum pan gasket.

 

[wilecgenius]

Iac

Hi
i had a problem with my 5.9 a couple years ago out of the blue when I started the motor the idle wouldn't hold and kept trying to kill the motor unless I kept my foot on the pedal. Once I had it running on th road it seemed to hold its own but when I would start it up acted up. Took it to mopar and they couldn't find anything wrong. I replaced the IAC for s&g's and it fixed my idle problem. The truck still runs like new after replacing it.. It was under $30 to do it and took 15 min.

hope this helps

 

[Nck]

Had that problem just the other day. But today I replaced the TPS, and my truck runs like new. Unplug the power from your TPS while the engine is running, and if it kills the engine and makes a check engine light come on and stay on, even after you plug the power back in then that is most likely the culprit.

 

[liljohn30]

Kinda have the same issue in my 08 hemi ram,at idle the truck sometimes dropped idle to where it almost stalled ,but the ecu catches it n brings idle up to say 1200 rpm...usually does it while waitn at a light. And it's spratic,I do know the idle seems higher ,it idles at say 1000..I cleaned throttle body out,but can't find idle air sensor or tps sensor