Check the ignition coil. Its possible that the coil has a broken wire inside that when the engine is cold makes good contact, but when the engine warms up the heat causes the wires to expand and break contact. Also check the ignition module, the same thing can happen there.
.045
0.035 in
35
0.035 inches.
.045
The spark plug wires connect in the 7,3,5,1, 8, 6, 4, 2 order on the 350 motor for the Chevrolet Silverado made in 1990. This changes in the models built after 1990.
Bad coil Bad rotor
Use the same spark plugs as you would with a distributor, but reset the gap to .020".
distirbuitor, wires; most likley. Just go through the whole ignition system.
its probly the condencer
Thay are between the valve covers and the intake. Thay are under the coils, take the coils loose and raise it up off of the plugs. It has a coil for every spark plug.
It would be best to discuss this with Pertronix.