87 tbi running horrible

[RednecK30]

I swapped a 95 tbi into my truck, and it has been running good, but lately I started to feel some stumbling on the highway, and on occasion when rescuing people from mud holes. then the other day after filling it up and driving 10 miles it wouldnt stay running. It will fire for about 2-3 seconds, and die. It will always fire back up just sometimes its a little harder to do. If I pump the gas I can barely keep it running. If I floor it makes a deep bogging sound and dies. It has shot a few flames out of the tbi as well.

I made sure all vacuum's were connected, and not broke, and put another EGR on it. I keep a spare TBI setup I put on it. New IAC, New coolant sensor on front of mani, new fuel filter, new plugs/wires/cap and rotor.

still wont stay running. with starter fluid runs like a champ.

on the intake manifold there are a few sensor, and maybe a computer (not sure) that sit on a bracket. I borrowed my buddies "bracket" with all the known working sensors on it, and will plug those in tonite to see if that resolves it... really those are the only thing I havent replaced minus the pump, and main computer, and o2...

Now I did put a fuel pump tester gauge where the fuel filter goes... Now I dont understand my gauge, but I am pretty sure its reading 15psi. (gauge reads 1-10 psig) assuming it goes by 10's? and it reads 1.5 and holds it for a good 5 minutes. I just assume it goes by 10's because most vehicles fuel pressure is 40-70 psi, and the gauge reads 1-10... I could be wrong. If I am then I assume my pump is bad.

Now i do have dual tanks, but the other pump is dead (or the switch doesnt work)...

any Ideas on what it could be. any experiences?