Hi there , when I press the gas pedal, the engine cuts out and backfires like fireworks. I have replaced the spark plug wires and the idle valve, but the problem persists. The check engine light is not on either. When I press the gas pedal slowly, there is no backfiring, but when I press it quickly, it backfires and cuts out. Could it be a problem with the fuel pump or the coils? Thank you for your help.