2000S4 issues - Part 2
 

Problem solved, I thought I would share the result, especailly with my new buddy Reefer_Bob.
EGT sensors...fine (suggested replacement cost $500)
O2 sensors....fine (suggested replacement cost $500 for all 4)
Coil packs...fine, spark plugs fine (but replaced anyway).
Real problem - MAF Sensor.
As I mentioned in the original post , I don't like the concept of throwing $ at a problem just hoping to fix it. Based on recommendations I would have burned over $1k with no results.
Thanks to those that did offer real help.

f'in a cotton! f'in a...

Glad you got it sorted out. You might x-post your fix to your original problem to help out others
 

that have similar symptoms.

How did you figure out it was the MAF?
BTW, the bosch MAF in 2000 S4s are prone to failure.

"So pretty please with sugar on top, change your f'ing egts"
 

so now I should change the cotton?

If you can dodge a wrench, you can dodge an egt!

nice, how did you figured it out?

Dodge? no, its an Audi
 

now I'm goofing on you...;)

Some logic and some investigation
 

The failed sensor answer couldn't really apply since the trouble occured even when dead cold - the EGT and the O2 both need a short warm up period - you can unplug the O2 sensors and the ECU will run on a default value.
It turns out you can do the same thing with the MAF, the ECU uses RPM and throttle position to approximate a air flow value. As soon as I unplugged the MAF it ran much better.
A little more research shows up a weakness in the 2000 MAF sensors, should be replaced with the latqer Hitahci unit.

You can replace with a Hitachi but it's not plug n play.
 

Need software for a Hitachi car (01/02) and recode the instrument cluster.

When I popped a pressure hose my car wouldn't run for crap even to limp home. Unplugged the MAF and started right up and ran fine.

Nice troubleshooting! I hate throwing money at a problem when a little tinkering can find the culprit.

Congrats! Totally overlooked that as a potential cause. :-(