I have a 96 gmc 1500 and it back fired and cut off and would not crank back up but I can pull the number 3 plug wire off and it will crank but as soon as I put it back on it cuts off
check the firing order from plugs to distributor ,no. one is front left drivers side counting criss cross to right and left again to no. 8 at right rear,18436572 dis. cap coil side has coil+ 6428 and other has5372 from rear to front! rock on.
Sounds like your distributor cap or rotor may have melted or cracked allowing the spark from the coil to constantly ground through the number three wire, pull the wire from the plug, ground the wire and crank it while watching for spark, there should only be a spark a little over once a second, any more than that and you know you have an issue within the cap or rotor.