is the coils case or bracket it mounts to suppose to be grounded to the frame of the car to work. I am having problems with my car missing and skipping and the tach jumping around and thought i heard that the coil must be ground to the frame to work

 

not that i'm aware of. They usually have a body ground for stuff like that. Never heard of grounding the coil to the frame. should be grounded to the body, or a wire leading to the battery ground.

 

I had the same problem when I had TPI with an MSD ignition. My problem... the coil wire was too close to the white tach wire. I'm sure high energy in the wire was somehow bleeding over to the tach wire making it jump all over the place. You could try relocating the coil too.

Another thing that was happening... the hood was rubbing on the top two wires going into the coil (if you still have it mounted in the stock location). Eventually from engine movement it rubbed the plastic jacket off the wires and it would make them ground out effectively killing my engine or makit it miss a lot. Another thing to check I guess