Engine Idle at 1600rpm

Could anyone help me figure out what is wrong with my 99 trooper,
it idles high. How can i make it come down to 750rpm.
Thanks

Jungleman

Check for the obvious. Something is allowing more intake air at idle. Vacuum leaks, sticking throttle/binding throttle cable, dirty/stuck Idle Air Control, or something along those lines. If the problem cannot be solved with any of those items, you may have a coolant sensor reporting an erroneously low reading. Any error codes/"Check Engine" light?

if could be something as simple as your butterfly in the trottle body is carboned up and needs a good cleaning. Or it could be a bad intake manifold gasket.

Could be the power steering pressure switch. IIRC there's a gray wire that can be disconnected from the pump to check this.

I have an OBD II autoscanner that does not give me any error codes when i use it on the car, no CEL, checked the throtle cable all seemed ok. What i did was to swap the IAC from my 94 trooper, it started and was normal for a while, then the engine suddenly went off and would not start again. when i replaced the IAC with the original one that was in the car it started running at about 900 - 1100rpm and has been there for the whole of yesterday. Could it be that the IAC for the 94 trooper does not work in the 99? Also when i replaced the IAC in the 94 trooper it started idling at 1500 for 5 mins then came to 1100 and has been there till now.
Guys, THIS BEATS MY IMAGINATION, THE CARS ARE SPOOKING ME UP.

Rgds

Jungleman

Yep, for a 1999 3.5L (non throttle by wire)

1) IAC, vlv itself is bad, or port is plugged.
2) Gummed up boot at the throttle shaft end of the throttle cable (slap some silicone grease in there)
3) Idle up press switch on P-steering pump. Yank the grey wire
4) Dirty throttle body. Needs a spray cleaning around throttle plate.
5) Vac leaks. Those will typically throw lean codes.

G/luck
Joel