I bought a 99 5.9l v8 magnum about 2 months ago it has roughly 107,500 miles on it. It ran great but now its idling by itself, when its it park usually it goes from 1000 up to 1700 in between those numbers, spuratic but hasent exeeded 2000rpm. Sometimes it stops and drops down to 700rpm sometimes it doesn't. Once i put it in drive it goes down to regular rpms. While im driving though it is kind of spuratic, when i go over rail roads or bumpy roads the rpms are never in the same spot usually jumping from about 1400 to 1800 rpm. I repalced the IAC but it didnt solve the problem. Im thinking maybe the TPS or MAP. I wanted to get another opinion before spending anymore money. Thank you in advance.

 

Think I would be lookin' at the TPS......