94 Chevy Truck 4.3 missing

I have a 94 chevy truck with a 4.3L it has 81,000 miles on it it's got a auto trans. And its two wheel drive. I was driving home the other day and while sitting at a stop light it missed 3 times and died. I got it started and limped it home. The cat. Coverter was very hot. The check engine light came on 3 times and not for more than 4 or 5 seconds. It has been on a diagnostic comp. And it showed nothing. It misses really bad in fact it will hardly run and wont really pull its self. I have removed the converter, changed the coil, pickup coil, modual, plug wires, dist. Cap and rotor. The plugs are only 2 years old. And I changed the fuel filter. When I can get it to idle it idles very smooth, how ever it will only idle every now and then, you have to work at it hahaha. Any idea?