I can't really think of any better words at the moment to discribe whats happening but when I hit around 4-5k RPM's my car starts to kick like I was tapping the gas. I have a 98 A4 1.8T Manual. I am running a KO4 on a wetterauer chip if that helps shed some light. Anyway it was funky and I would appriciate any help figuring out what it might be thanks.

 

Its probably a boost leak my car was doing the same thing and I did a boost leak check and it was a broken hose I fixed it now its perfect now i can go over 4 k with no problems also do you fell like the boost drops by it self when you are driven because my car was doing that.

 

have you had the codes checked? Just because you don't have a CEL doesn't mean there aren't hidden codes in your ECU.