My 400 CI small block has a random miss. It occurs in neutral or under load. It can be heard in the exhaust and felt at the exhaust. It happens with the engine hot or cold, The miss sometimes feels like a single cylinder missing, other times multiple cylinder misfires in a row maybe 2 or 3, and sometimes the engine shuts off briefly maybe a ½ second or less and then comes back to life. When it misses you can see the engine jump. It feels as if the ignition momentarily turns off and then back on. It has a Summit HEI ignition, maybe 3 years old. The plugs, wires, rotor and cap are new. The 12-volt supply to the distributor is consistently there even when the random miss occurs. Bad distributor module or something else?