i'm not great at this stuff yet, or even good, but i might be able to help you think up a list of things to check.
-you might check the fuel filter
-airintake (make sure its not filthy or clogged)
those are just some basics that came to mind, may not help alot, but it may eliminate a few. sorry i can't be any more help than that, just thought i would try since no one else has stepped up to the plate yet.
guys, help him out cause i sure don't know what it is. GOOD LUCK.