big problem

I was recently given a 1986 eurosport coupe with the 2.8 mpfi. It sat
for many years when me and my friend rescued it. It ran fine, sat for
3 more months and now it doesnt run, it will start and then die after
it runs for about a second. I have replaced all tune up parts, new
distributer, fuel pump, strainer, fp wiring harness, coolant temp
sensor, coil, ecu, and i tryed to get a new fuel pump relay, but im
not sure which relay it is, there is a set of two on the strut tower
drivers side, with fuses on both sides, or there is one below that
which i didnt find untill i returned relay which changed nothing, and
also there is some nasty grease on all of the electronic connections,
i was curious if chevy did that from the factory or not, any comments
would be helpfull. I have spent too much time and money on this
project to stop now.

Did you drain the tank and clean it?

Have the entire fuel system professionaly purged / cleaned; along with the fuel filter replaced. This may make a big difference. As far as the grease; it's di-electrice grease. I'm pretty sure that's not factory - I don't think I've ever seen that stock. It's not hurting anything; but if it makes you feel any better you could clean it off and apply some new, fresh grease.

I replaced the fuel pump and cleaned tank and lines and put new fuel in, could the fuel pressure regulator do it?