Wires?
Cap?
Rotor?
Fuel Filter?
PCV Valve?
Searched for any hoses that might have fallen off?
Any holes in properly-plugged-in hoses? (Spray small amounts of engine start around your engine to find--works for most vaccume leaks)

There were a lot of other good ideas to check. I recomend cap and rotor replacement along with plug wire check. That's what fixed mine.

Just like yours, it went from running fine (morning) to running horrible when I next started it.

Try the rest of the list at that link.