I have an 05 Turbo GT HO and today I was reving the engine to 4k rpms ( I was in a car wash hub and wanted to hear the blow off valve whistle ) when it got a little past 4k rpms it didnt want to go any higher. It just started to sputter. It only does this in neutral. it revs fine and goes all the way to redline pefectly when the gas is punched or slowly accelerating. Is there a problem or is it because its Turbo'd
? It seemed like it was building alot of preasure in the engine and it wouldnt go any higher....