4Krpm Coupe quattro hessitation problem. Very long, but please help!

[Emre Washburn]

Hello fellow quattrophilles,
    I have had a running problem on my early build 1990 Coupe quattro for
some time now.I started out in July when I got a slight hesitation at or
around 4K rpm and a slight power loss through out the entire rpm range.
Occasionally if I push her past 4k rpm there will be an intermittent power
surge at or around 5k rpm. This all happened about 3 weeks after I got the
car, which was foreign to me, so I brought it to my local Audi/VW shop. They
dumped the codes and determined it to be a bad #2 knock sensor. It was
replaced but the problem didn't go away. They then thought it was the #1
sensor, but that didn't do it either. Eventually, I found out that when the
ambient temp was extremely cold and the engine had not been given a chance
to warm up at all, the Coupe would not hesitate, until the engine reached
operating temp. We also found out that if a new or cold coolant temp sensor
was put on it even thought the engine was arm and the ambient temp was warm,
it wouldn't hesitate. We tried different
knock sensors, tired a different ECU, got a new fuel pump/filter put it,
took the entire exhaust system off (thought maybe it was plugged up), tested
various sensors, tried the generic 3-wire O2 sensor, thought that was bad so
we put in the OEM O2 sensor, it's been looked over and over again and
nothing fixes her! I brought her to a stealership last week as a last-ditch
effort. They called me after having her for 3 days and told me they fixed it
(got error codes for knock sensor and MAF, they said a knock sensor was
wired up backwards an the CO test pipe was plugged somehow so they can't
test the MAF to see how well, or if its working at all). It's not fixed, and
I paid the 6 hour$ of labor, and now it idles funky. I am going to bring it
back and have them fix idle and bitch till I get some money back. Anyone
have any suggestions as to what it might be. Ask me questions about it,
there may be a few things I forgot to mention that we tried.

Please, Please, Please HELP! I live in Saugerties, NY, near Kingston and
Catskill. If anyone local could maybe help me out I would be willing and
able to pay.