think hard my friend. when you are pushing say 15 psi, your car runs fine, when you are at full boost / WOT you are blowing out the spark. i had this SAME exact problem. the guys at VW thought it was a coil or the ICU going bad or the MAF was dirty. first thing i did was re gap all the plugs to .28 and the car ran perfect at all rpm's and all psi. i got the flashing CEL too before i re gapped them. i am almost 100% sure you just need to check your plugs, and / or run a different plug.

 

ALL RIGHT ALREADY!!!! you guys convinced me. ill pick up four new spark plugs tomorrow. and regap them. that is if i have time. thats probably it. and if not, im im coming after all of you with a chainsaw!! ok for real though ill try that and report back. probably check the ecu as well just for ***** and gigs but it will most likely work fine without resetting it
edit-just to make sure its bkr6es for the plug right? i get my ngk's mixed up all the time

 

Some people say BKR7E for chipped. I'm not sure which is better but either should work, I think.

 

I had this exact same issue a few weeks ago, was the coil packs. Good news for me, since I'm 01+ the dealer replaced all four packs for free. I'd put money on it being your ICM or coils, depending on what year your car is.

 

if it is indeed coils, S4 coils work and they are the updated ones that won't blow. somebody check me on that