I'm no expert, but it sounds like something that happened to me when I had a Chevy Z24. Turned out it was the computer acting up and getting its signals messed up. Try pulling the negative cable for about 30 seconds from the battery. You'll loose your clock and preset radio stations. Re-attach it and start the car and go for a short run to let the computer re-learn the car. Happy CREWZIN!
CREWZIN