Steve W. wrote:
> An engine needs thre things to run
> Air, Fuel, Ignition source
> Air is a given unless your covering the air cleaner with a bag.
> Fuel - about the only thing you didn't replace was the tank, so I would
> say your OK there
>
> The symptoms point to a heat related failure. Some component is getting
> hot enough to shut down the engine.
> Since you still have fuel pressure when the engine dies it isn't a bad
> pump.
> It also isn't likely the EGR since they don't normally shut down an
> engine and then clear up when they get cool. They are either stuck open
> (which causes REAL bad idle on the 4.3 and an engine that will not idle
> hot or cold) or they don't work at all.
>
>
> Ignition?
> You said you found a cruddy wire end. One usually won't do much but
> cause missfiring in that cylinder. I has a problem with the wifes 94 4.3
> that was a bad set of plug wires. It caused massive missfiring but no
> real problem with running or acceleration. Just bucking under load.
> (common symptom FYI).
>
> Bad plugs- Not likely since they fire OK when cold. Plus for the engine
> to quit they all have to stop working.
>
> Plug wires- Same as above BUT they could cause crossfiring.
>
> Cap - Usually causes missfires if the cap is bad.
>
> Rotor - possible but not real likely.
>
> Coil- very possible- it could be shorting out internally when it gets
> warm enough.
>
> Ignition Module - possible for the above reason, but they usually just
> fail.
>
> Computer - It's not showing codes which is not unusual for an OBD I.5
> vehicle (oddball that GM used in 95 on some vehicles) they mainly show a
> code only when an item totally fails, unlike OBD II that can tell you
> that a sensor is just getting weak. It could have a bad connection on
> the main connection though.
>
> Main wiring harness connection on the firewall - It has been a culprit a
> few times for heat related problems. It gets warm and the connection
> opens.
>
> It is also possible that it could be a bad connection to one of the
> above components.
>
I think I'd elmintae fuel entirely for the most part and at least slap a
gauge on that fuel pressure. Run it and shut it off see if it holds
pressure. See what the presure is when it stops running for the hell of it.

Sure the EGR is carboned up inside?(it should be getting close by now).