At first I thought it might be the wiring harness problem, but that only applies to 1992-1995. See this thread if you want to read about it.

http://www.peachparts.com/shopforum/showthread.php?t=128181&highlight=wiring+harness

Other than that, I would suspect a spark problem. Oil changes don't usually cause this sort of problem unless you inadvertently disturbed some wiring. Maybe wait until it gets dark outside and open the hood to look for stray sparks. Good luck,
Don