Well, got my first check engine light tonight.
For months now, on occasion, the car would "chug", have slightly uneven acceleration, and pulse at idle. It only happened very, very rarely, so it was fine.
The car had 150k service performed last Monday, and they said there were no codes (I assume they pulled pending codes as well.) New spark plugs, fuel filter, the works...
This did not solve the occasional chugging. It's just been getting more and more frequent, but I do not believe the service to be related at all. Tonight, it came to a head. It chugged the whole way home (14 miles or so). It chugged at stoplights, threatening to stop. It ignored the accelerator for a random amount of time, then suddenly surged forward quickly enough to throw me back in my seat and maintained that until I let off. The RPM would slowly drop with my foot in the same position on the gas as the car slowed down, then it would rush forward. The RPM drifted randomly with my foot exactly in the same spot on the accelerator. It pulsed in neutral as well at lights.
I wondered "why weren't there any codes? Why didn't the CEL come on?" Well, just as I pulled in my driveway, it did.
I'm not sure I feel safe driving it to my mechanic unless I have to (5 miles), so what should I check? This is worrying me a lot...
Really, really appreciate any help!