1995 Chevy Blazer Stalling/Choking out

I have had this car 5 weeks now and 3 out of 5 it has not run. The first 2 weeks it ran like a champ. I had one insident where the temp got high but didn't overheat. Decided to take a long road trip @ 80 miles. Got almost there and the truck started to choke out. Like it wasn't getting enough gas. I'd accelerate and the truck would even out. Eventually the engine stalled out and I couldn't get it back started. Since I had it towed I replaced the spark plugs. But at an idle the engine would choke out. I found a wire that wasn't properly grounded and the engine started. The truck ran for about 15 miles than choked out again. I had it towed again. They got it to the shop and she turned right over. They were unable to replicate. I drove the truck that night @30 miles, no problems. Tried to drive to work the next day stalled in less than a tenth of a mile. TOwed agian, they ran the truck till it was almost out of gas, never stalled. I now have it at another shop to no availl. The Fuel pressure is between 60-80 psi consistantly, I changed the fuel filter and plugs, engine has spark, the fuel pump is less than 8 months old, the engine is recently rebuilt less than 20K, the trans is also rebuilt with less than 30k miles, I do know there is an intake manifold gasket leak (exhaust). Any suggestions.