Thank you for your help and interest. I would like to fix the problem myself but it doesn't take long before it is beyond my expertise. By "recover" I mean that I was able to restart the truck with some difficulty after letting it sit for a few minutes. It ran well for about 15 miles and I thought that I had solved the problem with the gas treatment. Then it started to sputter again and backfire (not often though) through the exhaust pipe. I stopped again for a few minutes then got home. I haven't started the truck since. The air filter is an oil bath one but the oil looks pretty clean. The truck was in the body shop being restored for almost two years which probably didn't help the gas.
