I have been having a couple of issues simialr to what you are saying. So, I deleted all my 'handy' work. Wastegate change, ram air, and such. Took ram air off first. Nothing changed. Then I put the wastegate back to normal, and now I have seemed to gain all my power back. The only thing that seems to have stayed is the little missfires b/w down shifts when making a turn. This also happens if I give a slight rev. at the light just to hear my exhaust. "The motor just kinda misses a beat. I am going to leave my wastegate at normal. I didn't realize how much power I had lost. I feels like I have my dude back. Now, I still have an appt. on the 25th to find out what the missfire crap is about.

 

Let us know how things to at the dealer. I have two quick questions for you:

Did you ever have the car stall on you?

How did/do you change the wastegate setting?

 

Possibly crappola in the fuel rail or injector.

 

Looks like the problem went away. Filled up with a new tank of gas, but I also noticed when taking my air box cover that the filter was dislodged. So, it looks like one of the two caused the issue.