For '97 and '98 TJ's, there was a TSB for a similar MIL problem while decelerating, TSB# 18-08-00. It would set a code P0107, MAP volts too low, caused by long decel at closed throttle, over 1500 rpm. It would store a code if this occured. The TSB repair involves reprogramming the PCM. This TSB does not apply to the 2000 model TJ. I see no reflashes for it, either looking at Alldata.

Another issue might be that under a long closed throttle decel conditions, right after starting a cold engine, the engine might not get hot enough, and would set a "Engine too cold" fault. The PCM will shut off injector pulse (No fuel) at high vacuum, closed throttle conditions, over a certain vehicle speed. The PCM needs to see a rise to at least 140* in the first three minutes. If the engine gets no fuel, it will not build heat. This code usually will not set a light for this code, but a code would be stored in any event.

Can you run the Jeep in the same way that sets the light flashing while a buddy holds a scan tool watching for any code/s while the light comes on?