Neverending engine troubles 2.3 AAR

[Niklas.L]

Hi,

My name is Niklas and I'm from Sweden. I own a 1992 Audi 100 2.3 quattro with close to 360.000km on the clock. I have been having trouble getting the engine to run properly since the day I bought it, bought it knowing it didn't run as it should. Have been writing on a swedish forum, but they are giving me the silent treatment at the moment. So I thought I would see if you guys could help me sort out the issues.

Have been replacing and troubleshooting quite a bit so I thought I would give you a quick run through of what I've been doing.

When I bought the car it ran like shit more or less. It was misfiring and hesitating on full throttle, ran 10x worse when cold. Had to keep the pedal to the metal for it to pick up speed, which it did eventually. After 1km or so it started to run better, on half throttle or less.
Changed the spark plugs, rotor/distributor cap and the ignition cables. Cleaned the throttle body and air flow meter. The car ran better, but still had its issues.

Changed the oxygen sensor and the knock sensor. Again the car ran better, but with its issues.

Changed the fuel pressure regulator, the black plastic thing attached in front on the fuel pump. It started running better when cold. Didn't drop revs when idling if cold. Before it went from 1100rpm down to 200rpm and slowly worked its way up again. Also didn't hesitate as much when giving it the beans. Almost nothing.

Changed the o-ring for the vacuum pump because it was leaking oil. After this I started getting problems with it going between 1100-1400rpm when warm on idle. Found out it was the air flow meter so I change the whole package on top of the air filter box. The idle was ok again, but the car is still hesitating/out of power at full throttle and once again started running like shit when cold, not as much as before though.

Other issues with the car that I havn't had the time or motivation to fix is the head gasket. It leaks both oil and coolant. Not that much coolant, but I have filled roughly 6-8 liters of oil during the 18.000 something km I've drove with it. Also leaks a bit breaking fluid.

Right now I am out of ideas and more or less motivation as well. Hope you can help me sort out the issues I'm having!

Niklas