Intermittent rough idle and hanging rpms


Aug 4, 2020
Seattle, WA
2000 3.8L, 196k. Newer plugs (I think iridium?), new coil, cleaned IAC, 2 rounds of techron on 1/2 tank, no CEL. Still need to grab wires. Engine is smoother since I did the coil.

Engine was hanging a little high sometimes, no higher than 2k, but can be coerced down in gear and doesn't go back up on its own. Usually happens before operating temp. 100% of those times that it's hanging, it'll hang until I come to COMPLETE stop, then settle down to 700. Since the coil it stopped. Until tonight out of nowhere, after several separate trips out today.

However, the one that I originally tackled with the ignition pieces is this thing where I'll drive to a store, go in for 5-10 minutes, and when I start the car suddenly it's coughing and sputtering and acts like it's going to stall. If I try to give it constant throttle to bring up the rpms and smooth it out, it refuses until about 5-15 seconds in, at which point it seems to move on like nothing happened. Thought it was crap ignition. That also just happened again tonight out of the blue, after hanging rpms on the way to the store (but not on the way back).

I've poked around a couple times doing a quick visual and auditory check for vac leaks to no avail. No misfire codes or any others. The majority of the time it runs just fine, feels strong and doesn't complain. No odd noises or smells.

I'm at a loss. My final guess is maybe oil getting into the cylinders and coughing it up? The intermittent part is making my head spin.

Also PS, why is it that there are literally no UD pulleys listed as compatible with the 2000 aside from the $540 motoblue lol (no need to flame, I know I know. Just having fun with this thing)
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