very true, but do check all plug wires and make sure they're all on good, cause that could cause backfireing...but it is sounding like an opti

 

Throwing any codes?ses light on?due to backfiring i tend to also lean towards opti.if it's doing all that it should have a ses light on and throw codes.if not does the light work?does it come on for a few seconds when first starting the car?if not ses light might be defective