A month ago or so my car started feeling slow for some reason. Well today I realized that when I start the car and 2mins after or so if I WOT it, it'll pull like crazy. After 10 mins or so of driving, if I WOT it, it'll drag it's sorry a$$ and when I hit 4500rpm in whatever gear, the engine or something starts to whistle until I shift and then does it again on the next gear when I reach 4500rpm on that one.

It's hard to explain but I'm sure you get the picture.

Could a complete engine tune-up solve my problem?

 

It will not hurt to give your car a tune up.