Cuts out?

Hey guys I've looked everywhere and I've found nothing so I figured I'd ask here.

My buddy has a 87 Mazda B2200 and it cuts out and dies and misses once it warms up. It doesn't run great when it's cold but at least it will run. He's replaced the coil,dis cap,rotor,fuel pump,fuel filter,cleaned out the gas tank,spark plugs,plug wires,carb gaskets,cleaned the carb,air filter,and even the main fuses, anything and everything and it still does it........ We are pretty sure it's not a fuel problem. so what ya think it could be? It ides great and as soon as ya give it gas and try to get going it just shuts off. Dies in the middle of driving if you gas on it. Really strange problem. Oh and it's got a weber not the factory carb with all the junk on it.

Here it is so you can see that there's nothing to it really I just know he's beyond angry with it.