cherokee4~4

I Have a 1998 Jeep Cherokee 4.0 with 130,000 Miles on it. When I Start my jeep without my foot on the gas the RPM's go up to about 2100 then within a couple seconds they drop down to about 1000 If I leave the jeep in park and let it idle.After about 2 Min it starts to Idle Rough and the idle will jump way up and down like some one is hitting the gas then letting their foot off the gas. If I Start my jeep and put it in Drive it idles perfect but when I Start driving it when it gets to around 30-40MPH The Jeep Bogs down and I Have to let my foot off the Gas then I hit the gas again and it goes perfect. And it drives perfect until I Park it. And a lot of times after the bog down My Check engine light comes on. It says both 02 Censors are bad. So in this past week I Have replaced My Catalytic converter Both 02 Censors Spark plugs and wires Fuel pump and filter Throttle positioning censor air filter I Have cleaned My IAC And cleaned the whole throttle body I Have checked the MAP Censor and I Still have the same problem. Can some one please tell me what is wrong with my Jeep before I go Crazy..

freegdr

i see you cleand the iac did you test it for proper function

cherokee4~4

How do You test the IAC to See if it is Working properly? Thanks for any info.

peep

2 torx screws to remove the iac, spray it with carb cleaner and gently clean it with your in-laws tooth brush. don't get rammy or twist or pull the cone, you can damage the mechanism. New Idle Air Control Motor is about $60 from Napa or your Chrysler dealer.

lolz_jeep

X2

cherokee4~4

I Replace My IAC Today with a brand new one and the jeep is still doing the same thing but with no check engine light.. So I Have replace in the last week The plugs and wires,The IAC,TPS,Both 02 censors. The Catalytic converter. A new fuel pump.I Have cleaned the throttle body. What else could it be???

freegdr

after all these things have been done all issues are still the same nothing is any better at all correct

xjmuddigger

take ur throttle body off and soak it down with carb cleaner,clean it,then get a new gasket,its very cheap to do and makes a big difference and also check for vacuum leaks,spray carb cleaner on the lines and look for bubbles,if u see bubbles....fix it

freegdr

heres a link with your same issues even when you replace a part does not mean it will cure the issue i think you need to test the tps for proper function its described in the post http://www.naxja.org/forum/showthread.php?t=1061262

cherokee4~4

I Have replace my TPS With a brand new one. I Cleaned my throttle body spotless. My Jeep is still doing the exact same thing. When I First start my jeep it starts up fine But after about 2 min of letting it idle in park the RPM's drop and the Jeep starts to idle rough. When I Start The Jeep put it in drive and go at somewhere between 25-40 MPH The Jeep will bog down and I Have to let my foot off the gas Then I hit the gas again and the Jeep Drives Perfect until I Park it. Then after about 10 min of the jeep setting with the engine off when I start it up the jeep does the same thing all over again..

freegdr

i understand this you need to test the tps with a meter for proper function if every issues just required swapping parts every body here would be a ase master tech what was the code for the cel light you had

freegdr

also very possible has vacuum leaks been checked for

cherokee4~4

I Have No Ideal how to do that. I guess I will have to take it to the Dealer to look at This issue is driving me Crazy.. I Figured since the TPS Is Brand New it should be working correctly...

cherokee4~4

I have not checked for Vacuum leaks YET.If The Jeep has a Vacuum leak wouldn't the jeep bog down all the time? The Jeep Only bogs down once the first time I take off then It Never does it again until I Park it with the engine off and go to drive it again...

freegdr

remember thing expand when they get hot and contract when they cool intakemanifolds are vry common place for vacuum leaks testing the voltage out put on tps should be confirmed b4 throwing any more parts into the issue