I have a 99' Cherokee classic, 4.0, aw4 and am having some issues. Check engine light went on and it started to idle @1200 rpm, which is high. Pulled the IAC and cleaned it. Still idling high. Had the kid at advance do the diagnostic and it said an intake code.. Figured the IAC was shot, purchased a new one and installed it. Idle shot up to 3000 rpm. Thinking that wasn't it, I returned the part and installed a new TPS? on the back of the throttle body. Still idling @ 1200 rpm, getting poor gas mileage and it prematurely shifts gears while in drive. Won't shift early in 1/2 or 3. Anyone recognize this? Would a good IAC combined with a bad TPS cause the 3000 rpm idle? Knowing this is the best place to ask, I came here.

 

try another tps. could have been a bad one.

 

Adjust your Throttle Valve Cable, I was on NAXJA the other day and got the tip. Tell us how it works out for you

http://www.naxja.org/forum/showthread.php?t=1015963

 

Also check to see if you have a leak at your intake it will make it idle really high with just a small leak.g/l

 

I thought about that and that could be it but the premature shifting raised an eyebrow

 

It would really help if you could post the actuall error code reported.

 

It just gave a generic code. No numbers unfortunately. I change the IAC (ruined it) and put a new one in. Could the MAT sensor cause this? Now when I start it up it goes to 3000 rpms. Tried the throttle cable thing with no luck.

 

I also cleaned the MAT sensor. If its shot, cleaning it doesnt matter. The MAT sensor being the one next to the firing order on the block?

 

I really need help!! This went from a perfectly running vehicle to a POS that is making me lose a day of work!

 

Unlikely.

Clean/Change IAC, MAP Sensor, Vac Line.

 

I have a new IAC, new TPS. The MAP sensor is on the side of the throttle body with a little tube correct? Your sig line adds to your credibility.

 

i had this same problem once. but it was a vac line that i forgot to hook back up after i changed my valve cover gasket. i sugest you check all your vac lines to make sure one doesnt have a crack. or a hole in it aswell the rubber elbows.

 

New IAC, new TPS, new MAP and it still idles @ 3000rpm. I'm ready to cliff this thing into a river! I am seriously out of any answers. I dont see any signs of the vacuum line leaking. The line towards the front of the motor just goes to the air cleaner and thats not clogged. Could the vacuum line be bad and I cant see it?

 

i can almost guarantee you its a vac leak

 

3k idle? sounds like a blown intake gasket to me.