Hi all...I am posting for my husband and since I was the one who suffered the event!
98 Silverado 1500 5.7 Liter Vortec (Right?) After about 20 minutes of driving in 90 degree weather, engine bogged down -deceration occurred to simply stalling out in route (not a lot of warning 5:00 rush hour traffic in capital city!) Attempt to restart, she turns over but never catches. Let her sit for about 30-45 minutes,cooled off a bit and she restarts -travel on for about another 30-35 minutes, then repeat of same event for the next three hours. ( I did have a few choice words for her!)
Called friend who is a mechanic, instantly suggested replacing the ignition module. Did so....still same problem. He is coming over to check codes some time this week, because even though I LOVE this truck....I don't trust her right now. Any other suggestions?

 

I don't mean to be rude but have you checked the coolant level?
Ithas the symptoms ofan engine seizing up as it overheats due to lack of coolant.

Cheers

 

If the engine seizes, it doesn't usually "un-seize" itself. and if it did, it would have one hell of a knock to it.

My first thought was ignition module as well, but seeing as though you've replaced it with the same results, I would start ooking at the crank sensor

 

I don't think the suggestion to check the coolant level was rude, that was the first thing I did. Then checked oil and other fluids just for the sake of covering everything. No knocking in the engine....when she runs she runs smoothly and then suddenly after the 25-40 minute mark she just boggs down and cuts out. Thanks for the ideas and help. Our friend should be over sometime before Friday to check the codes.

 

why wait till friday? go to any major parts store, they all scope codes for free.

 

Maybe the fuel pump is starting to take a dump?

 

The same thing happened to me and it was the crank sensor going bad.

 

Fuel Filter. Seen it happen on that vintage Chevy pickups dozens of times.