91 Dodge W150 Complete Power Loss

I have a 91 Dodge W150 V8 5.9L. I had the engine rebuilt and had a bunch of smog equipment installed on it to get it to pass CA smog. The truck has absolutely zero power, when I first start it up I can drive about 40mph max. After about 10 minutes the truck will bog down to about 15-20mph and wont go any faster. If I pull over and stop the truck and let it sit for a few minutes I can start it back up and drive 40 then it bogs down, rinse and repeat. I can only push the gas pedal down a little bit, If I apply any more pressure or if I push the gas pedal past that limit it sounds like the truck starts sucking air, I get complete power loss and if I dont let off the gas the truck will die. Going uphill the truck will lose almost all power and just barely crawl up the hill, if its too steep the truck will come to a stop and wont move. I just replaced the wire harness, alternator, spark plugs, distributor. It had a new throttle body put on it when the engine was rebuilt. I took it to a mechanic to get the fuel pump replaced, however the mechanic was really shady and the problem was still present after. I removed the catalytic converter to see if that would help and it didn't. Any Ideas?

Also the colder the weather is the longer the truck will drive at 40 mph.