Just today I was starting up my truck and when it is not in a gear it idles extremly high for idle, about 1200 rpm. When normally it would idle at about 600-700 Any ideas on what might cause this?

 

Have you done anything under the hood lately? Mods or otherwise??

 

Mine does the same thing, on occasion. I have an '01 4.7lL. There aresome otherthreads on this forum and in the Durango forum about similar problems.

The idle on mine also surges on occasion. Normal idle is around 650 - 700 and occasionally the idle will inexplicably surge between 650 and 900 RPMs on one second intervals. The idle goes up and down, up and down, like clockwork. It "seems" to do it more frequently when the AC is off, but it does happen on occasion with the AC on. No codes are being thrown.

If you do a search on "idle surge" you'll see similar posts about this.

I've recently cleaned my fuel injectors to try to solve this problem. The truck definitely runs smoother, but the idle problems still exist. I am going to clean the throttle body next, and do a vacuum test to see if I have a leak somewhere. I'll probably just do some regular maintenance and replace the rubber vacuum hoses. If I figure this gremlin out, I'll let you know, but so far it's escaping me.

 

I would say start with the throttle body. Clean the IAC and the TPS.

I started mine up a couple of months ago, and the damn thing was idleing around 2200! I was like, WTF!?!?!? I pulled the IAC, and a piece of plastic had broke off my intake temp sensor, and lodged itself in the IAC. Pulled the piece of plastic out, and cleaned the IAC since i already had it out, and now it idles smmoooooooth! Right at 600. -Just glad the plastic didn't make it past there and go into the intake!

 

Yeah....the more i think about it...sounds like a vacuum leak. I say smoke test!