My 1999 blazer 4 wheel drive with the 4.3 vortec has an issue that just wont go away. I have replaced the plugs wires cap and rotor multiple times with acdelco parts and my cylinder 4 misfire keeps coming back. It runs absolutely terrible and I'm tired of putting money in it. What else could it be? I've also changed my coil and spider injector.

 

try doing a compression check to make sure you dont have a bent valve or a cracked ring.

 

I just found that the coil wire is arcing at the coil and distributor cap. I'm thinking that might be causing the misfire. Does that mean the coil is bad or what?