Got about 2 mile from my house today and my car started backfiring horribly. Everytime i tapped the gas. Wasnt even drivable. At first i thought my rear went, any clue what it could be? Could a bad opti cause this? Heres some info on my car

95 z28. All bolton mods, no internals touched

mac headers to slp exhaust, no cat

small timing cover leak.

Water pump went about 8k miles ago and was replaced
but the opti hasnt been replaced since i bought the car with about 20k miles ago