There is a bulletin for a startup idle problem and it requires the power train control module to be reprogrammed.And if your vehicle is under 8 years and 80,000 miles the repair is free at the dealership.Here is how it reads.
This bulletin involves selectively erasing and reprogramming the Powertrain Control
Module (PCM) with new software (Cal level 00Cal15C.).
2000 (TJ) Wrangler
2000 (WJ) Grand Cherokee
2000 (XJ) Cherokee
NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 4.0L (ERH)
ENGINE, CALIFORNIA EMISSIONS (NAE), AND CALIBRATION LEVEL PRIOR TO
(LESS OR LOWER THAN) THAT LISTED IN THE OVERVIEW ABOVE.
Some vehicle engines may exhibit a rough idle and/or MIL light "on" condition upon initial
start-up after a cold soak when temperatures are below 50 F (10 C).
There is also a possiblity that your "IAC" idle air control valve is stuck or binding.You can remove it from the throttle body and clean it with carb cleaner and try that.But usually they need to be replaced.
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