03 Cobra, Boost Problem?
 

I have an 03 Cobra w/ 60,000 miles and I am having a problem. When I'm full throttle the boost gage goes up but I'm getting eally bad surging. The car is pulling hard but should be giving me more. The car was running hot a few days ago. My friend was trying to put water in the radiator. He accidentally put water in the intercooler reservoir. I dont know if that is my problem or not. Any ideas!?