I have a roller 347 stroker, out of an 89 HO mustang block. the cam is ground for an EFI or carburator. it currently has a Parker Funnel Web intake manifold on it, with a 770cfm street avenger carburator. the ignition system is a mallory unelite destributor, and pro-coil. the problem is that the car wont tune at all. i've put a new distributor in it, timed it repeatedly. it's only made one decent pass down the 1/4 mile but then the very next day when i started it up, it was miss-firing and i've run out of things to try. if anyone has any idea what could be going on, anyhelp keeping the car on the road would be appriciated