Alright, I feel like quite a few people are posting about clutch issues. So here's the how to. The clutch is pinched by the pressure plate up against the flywheel to drive the transmission input shaft, what you're describing sounds somewhat like clutch slip. What happens when the clutch is slipping is that the engine seems to have a "breaking point", it'll provide power fine up until a certain TQ value and then the clutch starts slipping, applying more power only serves to make it slip more and damages the clutch friction surfaces more. There are a couple reasons that your clutch might be failing, the most common with this car is that people are riding the clutch too much or are actuating the clutch too slowly. Both of these will cause a low friction condition where the clutch is heated up and begins to glaze it which makes it a terrible friction surface. I had this begin to happen when I had my 06 LT a year after purchase, I sold it at 90k 2 years later and it was fine. How did I fix it? The advice I followed to repair the damage was to never shift below 3k, and always engage and disengage the clutch as rapidly as comfortable (not sidestepping the clutch pedal). Not even a week later the clutch was good as new. To prevent it from happening in the future keep your foot off the clutch when you're not using it, there's a dead pedal on the left for just that reason. Shift above 3k and don't burn the clutch by babying the pedal.