Engine dies

I was driving 65 mph.when the engine died.It restarted 20 minutes later.I drove for 5 minutes,turned engine off,tried to restart 10 minutes later.No start.Towed truck home 1.5 hrs.later.Truck started up.

Truck is 1997 Chevy Blazer,4.3 liter

The first step in differential diagnosis is does it crank and not start or no crank.
Step two, if it cranks and does not start, no spark or no fuel pressure.

Sounds like a classic failing coil (from heat).

If the coil/coil pack is seperate from the distributor and accessible you may be able to verify this with a heat gun…try a hair dryer on high. Warm the engine up and then, with the engine running, hold the hair dryer on the coil/coil pack. If the engine dies you have the answer.