Heat can do some funky things, especially to electrical systems. Expansion of metal, plastics, and rubber all have different amounts of expansion. If you have a poor connection that depends on the plastic or rubber to keep it in place, once that non metal item expands it will break the connection. Likewise with say...plug wire. It gets hot, expands a little and starts sagging, then it falls against the head or some other metal on the engine, wears the insulation off at that point over time and then shorts out the spark to that plug.
Check your plug wire to #1. Look for rubbed areas. Check the connections. Likewise with the injector wires.