random Cut out of the engine

A buddy of mine has a 89 chevy blazer with a 4.3 liter. He has done some massive modifications on the blazer, and has had to remove the engine to get this work done. When the engine was put back in about 2 weeks ago and finally started, it would run for about 3-5 minutes start to sputter, where upon the computer tried to compensate and starts shoving fuel through the injectors. After that all happens it dies. We thought it might be the fuel filter, vacume lines, or an ignition issue, but after replacing the filter, replacing the ignition system (new distributor, rotor, plugs, wires, and adjusting the timing), and checking the vacume lines the problems persist. Any suggestions??

Sounds like a fuel problem. I would run the engine with a fuel pressure gauge hooked up to see if you're losing fuel pressure. I believe that the fuel pump power runs through the oil pressure sender. Is it still hooked up?

Sounds like a fuel problem. I would run the engine with a fuel pressure gauge hooked up to see if you're losing fuel pressure. I believe that the fuel pump power runs through the oil pressure sender. Is it still hooked up?

That is the thing, the engine is getting pleanty of fuel. At times it smells almost as if it is funning a little too rich. We ran the engine with the air cleaner off to see if the injectors were working and all that good stuff and they are working great, and pushing out pleanty of fuel.

New Distributor?
When it dies, does it start right up again or just crank? As it's dies, is it giving off lots of black smoke? If it just cranks, that's the time to check for spark since you know it has plenty of fuel. If it starts right up again, make sure that it's not losing ignition power to the coil (pink wire). If that is good, possible ignition coil or module.

Check your timing with the timing wire unattached from the computer.

Well upon looking into the problem further we found that one vacume line is missing from the new intake setup that was put on. The blazer has been body dropped, airbagged, and is sitting on 20's right now. A lot of custom work has been done on this blazer. But we are thinking that maybe there is a vacume problem now. When the Blazer was baody dropped, the engine had to be moved up (vertically). But the engine sat so high that, it would not let the hood close at all. So my friend went out and bought one the biggest cowl induction hoods I have ever seen. That still didnt allow for enough space to close the hood. So he got an aftermarket intake. But there was a vacume line nipple on the original intake that no longer exists on the new intake. From what we can tell this vacume line has somthing to do with controling the temp of the engine. From what I have been told it helps to bring the engine up to temp. If you happen to know anything about the vacume setup I would appreciate any advice. thanks for the input.

inspect the engine totally and check all wiring and vacuum connection.