I’ve noticed over the years that my rpms dip down below idle whenever the car slows down. It’s not very bad over 10 mph because the car has plenty of momentum, but when slowing down from X to 10 to 0, you really notice and feel the car bogging down just before coming to a complete stop. Normal idle is 850 rpm, but when inspecting the tachometer, it comes down to 650 when slowing down to a stop before resuming normal idle. This effect is much worse when car isn’t driven for 72+ hours. I have a video of revving the car to demonstrate what happens. Does this mean my etm or maf is going bad? It’s not a drivability issue right now, but has been slowly getting worse.

Update: I took the car on a long spirited drive, and at one point really opened it up to 5000 rpm while going from a stop to 70. That seems to have dramatically improved how the car behaves, and it doesn’t dip down very much at all. Instead of dipping down to 650 and vibrating like crazy, it might dip down to 800 at the lowest and it’s hardly noticeable. I guess it just needed to be opened up.

Had throttle cleaned by a reputable mechanic. Problem disapeared.