'90 200 tqa running poorly Fixed

[Nick Lawrence]

The moral of the story...inspect what you expect.
The first thing I did was install new spark plugs, nothing changed. After many hours of checking everything else, and getting very frustrated I enlisted some  help.  
When we went back to check compression again, looked at the plugs and one of the tri-electrodes  was bent over touching or nearly touching the center electrode.  How it ran so well under boost I don't know, I didn't notice loss of power. 
The plug I installed came out of a good box and the cardboard tube wasn 't damaged so it had to have been packed that way.
Happy Audi again.
Nick
----- Original Message ----- 
From: Nick Lawrence 
To: quattro at audifans.com 
Sent: Monday, July 18, 2011 9:36 AM
Subject: '90 200 tqa running poorly


Vehicle is 1990 audi 200 tqa.
After a few stop and start errands Sunday the car wouldn't start. it would crank and occasionaly fire and quit. I swapped the fuel pump relay, then removed and jumpered the relay. I pulled off enough covers to hear the the fuel pump, it was humming.
After sitting, fiddling and cussing for about half an hour the car started but ran rough and really felt like missing.  
Made it home, replaced the spark plugs no change. 
However mash the pedal and it will rev and boost the normal 1.8-1.9, feels like normal power.  but back at idle and low speed still bucks and stumbles.

I swapped in another dist cap and wires.
It will stall when  the oil cap is loosened, but not when the dip stick is pulled. (I thought it used to)
I checked compression    130- 150 .
If fuel pressure was off could it still run boost and have adequate power?
If the oxygen sensor failed would the car run really bad?  In my million miles of Audi's i have never experienced any change good or bad when replacing oxygen sensors.
Anybody ever see an ignition coil fail in this manner?

Hoping for more ideas to check out.

Nick  central Ohio