Ok heres the story,

I drive a 1995 audi 90 quattro with a 12v v6. Over the weekend, I took the intake manifold off and ported the exit runners to match the heads. I also polished the casting marks on the inside of the manifold. I also did some light porting and polishing on the throttle body. I put everything back together and fired it up. The car has a little hesitation when you first floor it but i'm guessing thats because it is running lean.
The problem is that after the car has been running or cruising for a while at a constant rev, The car looses control of the throttle. The power starts to go away if you add gas the car will switch between wide open and dead. If you floor it the starts bucking really bad. Its like on, off, on, off, on, off. If you shut the car off and start it up again, the bad stutter goes away.

Here are my theories;
the lean fuel/air ratio is messing with the ECM
something is wrong with the EGR
something is wrong with the TPS

I don't know what is going on. I'm waiting for a cable to come in the mail so I can read the code on a scanner.
Any Ideas are much appreciated

THANK YOU

 

I fixed it. it was the TPS.