Stuttering when accelerating
 

99 v6 manual Camry (260k mi) recently began "stuttering", for lack of a better term, when accelerating. Only shows up in 2nd-5th, never in 1st gear, even when flooring it. Never happens when accelerating very gently, usually happens when pedal is 1/2 to 3/4 depressed and above 2-3k rpm. It is hard to describe the stutter, it's partially a feeling and partly a sound, like a very quick rhythmic bumping. It is definitely not loud or violent, and the tachometer is rock-solid, smoothly moving up - doesn't jump around or anything.


Things I've tried: sea foam (via gas tank, brake line, and oil cap), new fuel filter, all new spark plugs, lines to plugs are new within the past year, and still look new; air filter isn't bad. The "sock" filter on the fuel pump had a small amount of gunk on the bottom but was able to gently brush that off. Don't see any extremely worn or cracking lines anywhere. I've revved up in 5th from standstill and popped the clutch, which immediately kills the engine, so no slipping there.


I've tried to browse the forums but really don't know what to try without dropping more serious money. Engine mounts? CV joints? I haven't done a fuel pressure test yet, but since I'm able to rev all the way up in the first without problems, wouldn't that rule that out??


We did get some good used front tires within the last month, but it's my wife's car and we can't pinpoint if the issue started at the same time...


What are some other simple checks I can perform to figure this out? Thanks in advance!

Also meant to add that I haven't checked codes, as there is no check engine indicator on.

Does this stuttering happen more when the car is cold or does it matter?
Have you cleaned your MAF?

Thanks for the reply; temperature doesn't seem to matter, occurs when cold or warmed up.

I bought the MAF cleaner today, tore into it and found out that the MAF isn't servicable! It's not the wire type, it's shaped like a tiny jet engine, vane-type with a trap door that is activated by airflow. Since I have no codes I'm assuming it's working.

Not sure what to check next.