I have a 1986 Chevy C6500 firetruck with a 427 tall deck. After getting up to temperature The truck will randomly turn off and all of the gauges will drop until you switch the ignition to the off position and then back on, the truck will then backfire and the engine restarts. I have replaced the ignition switch, distributor module, coil, cap and rotor but that has not fixed the problem. The truck is also wired with a battery cutoff switch.

any ideas on this would be greatly appreciated.

 

Have you replaced the ignition switch?

 

I did replaced the ignition switch but it did not fix the issue.

 

Battery cutoff switch? Ok, can you wire around that?