Low RPM misfire , rich condition.
Do injectors work by % throttle, or are they controlled via engine RPM?
I also have negative fuel trims. (Rich)
More than likely you have a spark plug or coil issue easy to try switching coils see if a different cylinder begins misfiring or pull the plug and have a look
how many miles on your car?
I had the car serviced for another reason and asked to diagnose this too... they found nothing, no codes, but also felt it... they said sometimes this happens as a precursor to the intake manifold failing and to watch a few months to see if it throws out that code (which it did maybe 4 months ago and I erased it, then had my head bolts replaced in June).
I'll live with it until it is a bigger problem since I just dumped about $5k of repairs in at 99k miles... she just doesn't want to get to 100k cheaply...








