1991 Pontiac Firebird car runs good then doesnt run at all

We checked the pressure and the book says 40.5 pounds so we replaced the pump to find out that it was at 37 pounds and needed 34 to 47 pounds to run right gr hasle for nothing lol but edited the upper post with updats any ideas

Checked and re checked those right now im installing a new ecm ill keep you posted to let you know if thats the problem

Wasnt the computer grrrr

It is a tpi mpfi I got it some what running now im gona give it a tune up with new plugs wires dist cap and rotar to try and fix the rest of it couse its idleing and just running funny now but it is staying running

Ok now I really dont get I the car has new plugs new wires new dis cap and rotar new fuel pump and filter and still has the problem
we thought we had it fixed couse it ran good for 2 days but last night I reved it up in nueltrual and now it starts idels for a half a second and dies same as before but once and a while it will go back to fine again and I can drive around all day it was fine till I reved it in nuetral then it started it again and wont come back from it. Anyway what its doing is
it starts fine runs smooths but dies like it losses spark or gas idk what it could be now when we changed the filter and dis cap it fixed the problems for the time being. But now its the same problem again with it starting fine idleing and dieing then somtimes able to be driven before it dies any idea would really help or if you need any information or and more details please say so this is getting really irritating I keep throwing things at it and nothing is fixing it and for a car I bought almost two weeks ago and only got to drive 3 days and stuck 200 into it so far its getting really depressing