So last week I installed Magnapaks and K&N CAI and kept the stock tune on my '09 GT. I drove it all week back and forth to work and got on it once or twice and everything seemed fine. Today I got on it in second gear and not sure of the rpm, but at about 4000, I think, it shut down and went into limp mode. I pulled to the side of the road and shut the engine and waited a few minutes. Started it up and everything seemed fine. I got on it again on the way home and it didn't seem to be any problem, although I don't think I got it up to the same rpm as I did the other time. What caused that? Is there something wrong? Do I need to do a tune? Should I take it to the dealer and will they just tell me that it's because I installed aftermarket stuff and charge me for repairs?