help me keep my piso running!

[Low87]

Well, the trucks at it again! After having sat for a year (been running 4 months now though) and 150,000 miles on the rebuilt 305, it never has run great. I have to warm it up for at least 20 minutes each morning (even when it was 100+).
A little background, it's got a Summit fuel tank under the bed, that and the sending unit have been in 4 months. The fuel pump was on with the old fuel cell (in the bed, got water in the fuel) and is about a year old, but maybe actually 4-5 months of use. The fuel filter is the same age. The TBI was rebuilt last year also, when I found water in the gas.
I changed the plugs, wires, cap, and rotor last week. The only bad plug was #6 which had a lot of buildup, but I've known for a while that the valve seal is bad there.
Today I gave it the usual warmup, I had to make a sales call in Bartlesville (hour away, test drive to see if I could make it to the OK meet). Ran fine at idle during warmup. I almost made it out of the neighborhood, when I slowed for the stop sign the engine slowed down fast then died. I would turn over and over but not start. I got out and checked the tank, almost full. I finally got it to fire but it died down again. After about 5 minutes it started, I backed up about 50 feet, and it died again. I got it started again and made it home by keeping the gas down and using the brake to control speed. I popped the hood, found the cap was loose and the #4 boot had popped off, fixed those, and it still does the same thing. I'm thinking new pump and filter wouldn't hurt. Anyone have advice? I know I need a new engine, I have the bottom end of a 383 in the garage but lack the $$$ to build the rest. I need to keep this piso running for another year or so.