1988 ford f150 302 5.0 stalling?

I was driving my truck about 50 to 60 miles and all of a sudden it jerked forward a few times then stalled on me. Tryed to start it up and it would run then just die again. Acts like its not getting fuel. I just went through and pulled the whole motor out cleaned it up changed all gaskets because it happened the first time. This is the first time its happened to me after but its only drove about 80 miles total. It feels normal till it dies. It didn't pass smog due to bad catalytic converter the guy said but I cut it open and it looks clean. What would cause my truck to do this. Also I just started it up before I opened my cat and it ran just fine drove it like 30 miles. Only been 18 hrs since it wouldn t drive then now it drives just fine.

Uh, what?