90 camaro rs 3.1L V-6

My camaro was cutting out in power a few weeks ago. I was driving down
the road and it just shut off on me. I brought it back home and it felt
like a fuel problem, I changed out the fuel filter and checked the fuel
pump and the fuel sending unit and it is all working fine it just wont
run correctly. I took it to midas to get a computer diagnostic, they
told me that my ecm and my mapp sensor was out. I said ok I took the
car home put in a new ecm and mapp sensor and the car cranks over now
but hardly runs and runs really rough and if i touch the accelerator
the car shuts off. I have checked the air cleaner, replaced the
plugs,wires,fuel filter, ecm, mapp sensor, and I though maybe there was
loss of power on the battery but I checked out my battery alternator
and cables and grounds and everything is good and I just recently
checked the catalyc converter maybe it was clogged I thought but it
wasn't that either so I am at A loss here and I cannot figure out what
is wrong with my car. It has ran for the last year and a half and now I
take it out one day and it just shuts off on me and I give it routine
maintanance when needed and I am racking my brain here so if some one
could please tell me what is wrong with my car it would be much
appreciated thank you very much. My car is a 90 camaro 3.1 L V-6 High
performance model rs. If someone could please help me out please.