1987 gmc with code 42

[twoodson]

Make sure that the connectors are not coming loose on the coil. Mine did something similar and I called my mechanic while on the side of the road and he told me to check the connecters that connects to the top of the coil, one of the what i call snaps had broken so it would work its way up just enough to kill the truck, i mashed it back down and it restarted and I mde it home and went to the bone yard to get a good and replaced the broken one.