Stumped by strange problem

I have a 1999 Chevy S10 2WD Pickup, 4.3L V6, 106K miles that is making me crazy. Vehicle starts fine and runs to operating temp, then it shuts off. Once it shuts off I have to wait 3-5 minutes and it will start again and run for another 5-10 minutes before it dies again. My first thoughts were bad gas, but isopropyl and new gas didn't help. New air filter also did not help. It seems like it quits when coasting downhill or after slowing from highway speeds. Fuel pump was replaced approx 8 months ago, all was well until last week. Also, if I shut the truck off at temperature it will not restart until it sits for a few minutes. None of the "check engine etc." Lights are lit. It also seems like it idles rough and wants to quit if I rev the engine in neutral and return to idle in my driveway, but it will idle all day long if left alone. Any help is appreciated. Thanks!