[s-cars] S4 bucking under WOT - what else?

[Ivan Demkovitch]

Folks,

Same problem keep bugging me. Any time under WOT car would surge violently 
when boost starting to build up. Sometimes it would be just 1-2 surges and 
then it accelerate just fine and other time it will surge without letting me 
go fast :)

If I accelerate slowly - car gets up to speed just fine.

It used to be intermittant problem but within last month it started to 
become regular.

What I had done (thanks to advices here):
1. Replaced spark plugs
2. Replaced air and fuel filters.
3. Tested coils using "spark tester" test. All coils tested out fine with 
similar gap. Maybe 1 turn difference.

Yesterday I had to buy compressor (good excuse for wife and starting point 
to collect air tools :)
Tested intake for leaks today.
1. Connected 3' PVC plug to hose from MAF to pressurise all intake.
2. Got huge leak from oil cap
3. Read archives
4. Plug hose to valve cover
5. Pressurise again.
6. Got very big intake(MAF->Turbo) hose. Yes, it was inflated and ready to 
blow.
7. No sign of obvius leaks. Can't really test because was scared of that 
hose to blow up. 10 psi didn't show anything. 15-20psi quick check didn't 
show anything.

What else..

I have that "rattle snake" sound when let off gas. Thought it somewhat 
normal but apparently its not.

When I removed hose from MAF it had some oil in it. Looks like protective 
screen on MAF was wet. Is it normal?

Read archives.

Cleaned up MAF connector. I _think_ it improved a little. But this is not 
for sure.

Anyway. I stuck with what I have and have no idea what to do next.

If it's MAF - then I need to try good one before buying ($$$)
If it's coils - I'd rather go with 1.8 coils setup.

Anyway - don't want to spend money to replace different parts. I'm sure 
there is better way.

Any pointers on what do I need

Thanks for advice!

Ivan
93' S4