Free reving or in gear under like wot? Car won't free rev past 5k FYI.
Sounds like a misfire. As seen here post 3...
"Service engine soon" light and here...
Engine problem - p0300 - Whats the fix?. The cars are rich from the factory but yes they do lean out with mods. I've knocked on the dyno. Wasn't watching the light blink though. I wouldn't take it to the dealer only because you don't know if a tune was installed on the car before you bought. I'd check the plugs perhaps and while you may not be ready a tune might be in order or at least looked at with uprev.
The car was all the way hot right? Coolant and oil temp?