1999 Silverado, 1500ext, 5.7Vortec, 234,xxx mi. Had this happen several times over the 4 years I've owned it. Strong old 350 runs great, then starts missing for a few miles, then backfiring out the exhaust, then dead. Won't start. First time, mechanic replaced cap and rotor. I drove it probably 10k miles. Second time, same fix. Drove about 5k miles then parked it for a year due to health issues. Started it periodically to keep the battery up. A couple of months ago, I had it running, charging the battery, and it pulled the same trick. Started missing, backfiring, then died. No start. I put on a new cap and rotor. Fired right up. Drove it 15 miles ....yep. Same crap, AGAIN. This time I put a new distributor in along with a new cap and rotor. This time I got about 50 miles out of it before it did the same thing again. Luckily, I was in my front yard this time. (My ins. Co. is threatening to drop my tow coverage 😁). So, what do I target next? Coil? Fuel? Sensors? I'm pulling my hair out!!