I posted this in Chrysler forum but it is not to active over there. Anyway have a sebring JXi that at idle and in park the rpm will fluxuate about 200 rpm. The only strange thing is that the speedo will start moving anywhere from 0 to 55 mi an hr. This movement is not irratic. nice and smooth until it levels out fluxuating between 40 to 50 mi an hr. I can then give it a little fuel and it will stop for a minute then returns. Any ideas?

I have not done a thing to it yet. Was thinking I might have a speed sensor or something shorting out.

 

I'd definitely check the speed sensor and I'd have the tranny looked at as well. My tranny started doing something similar about a month before it went out on me.....would just drive fine and once in a while would idle funny or jump rpms while I was driving....wasnt very noticable at first....but got worse as it came along.

 

Now that you mention it, sometimes the car wants to take off when you take it out of park and barely step on the gas. It has also not wanted to shift into reverse I have to put it in drive then back to reverse for it to work.