I have a 1999 Jeep Cherokee Sport with the 4.0, auto 160K on the odometer. I did a tuneup about 5K miles ago (plugs, wires cap & rotor). I noticed lately that at idle sometimes I have a surging problems. Tach goes from 600-1100 rpms. I have to put her in neutral to prevent stalling. It only lasts a minute or so and then everything is back to normal. I do run the AC all the time. No over heating problems, (new water pump & radiator). No warning lights. I did notice last night that I took a hard turn in a parking lot and the engine stalled out. Started right up again. I did run some Sea Foam through the gas tank and no difference. Any suggestions? Thanks in advance. You guys have saved me a lot of $$$ in the past 5-6 years.

 

I have had this problem in the past ( still not completely gone ) and what I ended up having to do is clean the throttle body out several and went over all my grounds. The biggest problem for me ended up being that my Idle Air Control was getting pretty gummed up. Hope this helps.

 

IAC, ebay. Also check for any play in the distributor shaft side to side. With that mileage you can figure on replacing it. Use only mopar cps, I have 2 autozone ones in my glove box waiting to go back. Ended up putting the original cps with 200k back in the dizzy runs like a swiss watch/.

 

I thought it might be the throttle body needed cleaning. Thanks for the response.

 

Might sound weird but while it's doing that. Wiggle some wires around near the throttle body/iac.

 

What about the fuel pump? Considering it stalled out while turning in a park lot. Just a thought.

 

And of course the ever present vacuum leak. Should be a routing diagram under the hood. Good idea to just buy some hose and start replacing at the manifold.

 

I will check that this morning. Thank you

 

I replaced the cap with an upgraded Advance Auto model. Might check that again. The distributor was replaced about 10k ago.

 

Good idea. I recently degreased everything under the hood and sprayed engine detail liberally. I like working on a clean engine. Will check the hoses. Thanks.

 

Any luck?