What would cause this considering that my Stang is bone stock ?
I notified a BIG difference in the deccelaration popping\backfiring since I fill her up with 94 octane this morning
that was my first thought, but then he stated he has never checked it makes me wonder about the tune. maybe he has got a lot of carbon build up which is igniting the lower octane fuel. the higher octane takes more energy (heat) to burn and the carbon deposits can't ignite the 94. Should get tune up including obviously the timing checked.