Runs 20 then dies

80fbody. I done the old tried and true switch the ballast out. I carry a spare in the glove box. Yes the ballast gets hot but the ecu stays cold. Even the coil doesn't get hot. I had good current on both sides of the ballast and coil after it cuts off.

67dart273, I did bypass to the battery terminal to the hot side of coil and used a remote starter switch with the key on also. Still no spark. I will recheck grounds. I replaced the ecu after I tried ballast and replaced battery.