Engine

Do you have a check engine light on? If yes, then that's the first place to check. Have the computer scanned.

When was your last tune up? If it's been too long, then you should do this before trying to diagnose a problem.

Also check for vacuum leaks, water in gas, clogged fuel filter and faulty fuel pressure regulator.

With all engine problems, begin with the easiest things to check, ending with the hardest, in a logical order of course.