Check engine light lit? Pull a code. Fuel filter? Water in the fuel? Air filter? I pulled one off the yard bosses truck that had about an inch of brick fuzz growing off of it and saved him a valve job. How's your maintenance regimen?
Sounds like it might be time for a tune up.If you or someone you know has access to a graphing scan tool or an engine scope,take a look at the ign pattern.you can tell alot about whats going on with a quick scan.