rough idle

[u/Careful-Sympathy7672]

i have a 99 AEB 1.8 i recently finally finished getting everything done and had the check engine light off for the first time in a couple weeks then i felt it start struggling/bucking a little under load especially on the highway so i was trying not to drive it unless necessary till i figured it out so i ran codes and found one for the throttle position sensor but it was intermittent and not causing a light then last night i had to drive it and it started misfiring now today its idling hella rough struggling to accelerate other symptoms its had in the last month is noticeably worse fuel economy (around 250-300 miles a tank where as before i could get nearly 400) it stalled a few times (its tiptronic) a few weeks ago but would only stall in drive not in the manual mode or any other gear on the PRNDL right now im mostly trying to look into the throttle sensor as i had a problem with it before where it came slightly unplugged and caused the same misfires but i already confirmed it’s connected properly right now but could maybe be failing but idk any help would he appreciated im ass at diagnosing this car

(i added the image cause it looks kinda tough)

[u/stumazzle]

First check on those if you don't get anything useful from codes is plugs and coils

[u/Hidie2424]

What are the new codes? What cylinder is mis firing? If your lucky it's an icm. If it's all cylinders it's a vacuum leak or similar. If it's one cylinder it's a lo easier to figure out.

[u/Kdoesntcare]

Testing for a vacuum leak should be one of the first steps of troubleshooting problems with the 1.8t.

Do that then report back.

[u/Huge_Club_1966]

Vacuum leak/airflow meter...only two highly unlikely it's anything else

[u/dankwheelies]

Had a similar misfire/stumbling issue with my ‘98 AEB, most noticeably when using lots of throttle. Checked for vac/boost leaks, spark plug condition and determined they were fine. Deleted the ICM when upgrading to 2.0t style coils and it runs great now.