could be a few things, but i've had this happened to me before. check your spark plugs, timing belt, intercooler pumping, transmission and even check your battery. it's hard to say, but obviously something is limiting its power and not allowing it to reach its potential. no a serious thing i don't think, but get it checked out by a mechanic that knows about sports cars not any mechanic as they will rip you off and the reality is, sometimes they might not even know what to do.
good luck mate.