intermittent idle problem help please!

when i start my xj cold (98) it will start run and idle fine can drive as long as I want no problems. As soon as i shut it off and start it again within 6 hrs or so it will start fine and idle ok. As I get going down the rd within a coupla hundred feet i loose power. I can do 2 things, shove the clutch and rev it up to about 4000 rpm cleans it right up no more problems. Or i can just drive through it and it will clear up in about 5-10 seconds. CEL came on said I needed a new upstream 02 sensor. done. runs a little better but still have the problem. one time when i would stop at a light the idle would fluctuate (almost stall out then rev to 1400rpm) hasnt done that but one time. problem has actually stopped now for 2 days. CEL light hasnt been back on since new 02 sensor. Any ideas?

IAC (idle air controller)sensor or perhaps CPS (crank position sensor). Those are 2 of the usual suspects.

My jeep was having a similar mysterious idle/stalling/not re-starting problem. I did a complete tune up and it was still there. Replaced the IAC valve and while i was at it fully cleaned the throttle body. The old valve was covered in black crud, as was where it mounts in the TB and cleaned up a lot of junk from the TB as well. Fixed the problem, and easy to do.

mikeypmcg said:

when i start my xj cold (98) it will start run and idle fine can drive as long as I want no problems. As soon as i shut it off and start it again within 6 hrs or so it will start fine and idle ok. As I get going down the rd within a coupla hundred feet i loose power. I can do 2 things, shove the clutch and rev it up to about 4000 rpm cleans it right up no more problems. Or i can just drive through it and it will clear up in about 5-10 seconds. CEL came on said I needed a new upstream 02 sensor. done. runs a little better but still have the problem. one time when i would stop at a light the idle would fluctuate (almost stall out then rev to 1400rpm) hasnt done that but one time. problem has actually stopped now for 2 days. CEL light hasnt been back on since new 02 sensor. Any ideas?

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