I had the same problem with my 97vt.
when i first had the gas installed $2050.00 if backfired like buggery.
So I took the car to untratune and they suggested new plugs (with a gap of 0.9) and new leads,
to this day the car has not backfired.
I have since added a pod filter
when i first had the gas installed $2050.00 if backfired like buggery.
So I took the car to untratune and they suggested new plugs (with a gap of 0.9) and new leads,
to this day the car has not backfired.
I have since added a pod filter