So I was given a 1995 tbird 4.6l six months ago and the previous owner said it has always had a misfire under load at low rpms and does it ever. I proceed to do all the normal stuff: plugs, wires, coil packs, fuel filters but the misfire wont go away. I go out and buy a code reader, it throws a P0304 code cylinder four. So, I check if the injector is getting power, it is, they all are. I then build a jig to bench test the injectors, they all work properly and are clean. In a last effort I change the intake gaskets and inspect the valve train, nothing i don't see any changes. Is this a common problem with tbirds?