Engine stalls out

I was wondering if anyone could help me...
I have an 89 pontiac firebird, v8 5.0L

Engine runs smooth, when I first start the car, the rpm is abnormally high (when in neutral sometimes around 1400rpm) and slowly decreases until it gets around 700rpm...
similar thing happens while in drive, just it drops down to almost 500rpm...
anyway, my engine randomly stalls out, usually when in drive, but it has happened while in neutral... Usually I can just turn it back on and it starts,
but twice I havnt been able to... and I had to wait awhile
When I had to wait awhile someone had sprayed this special stuff in the intake and it started right up... as soon as he stoped spraying the engine stoped, so Im pretty sure its a fuel pressure problem?

anyway, I changed the fuel filter myself, that didnt work, so my next step is to change the fuel pump (was going to have a friend do that for me) Before I buy the part ect, I just want to make sure that actually is the problem,


any input is definately appreciated!
thanks for your time :)

Don't throw parts at it, check your fuel pressure. If the pressure is OK then you are loosig the refrence pulse from the distributor to the ECM. The ECM needs this ignition pulse or it won't allow the injectors to fire.

Im trying to avoid putting more parts in and loosing money...
anyway, Im kinda mechanic savy, but Im not advanced in any way...
how would I go about checking the fuel pressure?

Hook a fuel pressure gauge to the schrader on the back of the passenger side fuel rail (looks like an AN fitting with a cap on it). Turn the key on and purge out any air from the gauge line. Turn key off for 20 seconds then back on. Pressure should read about 42 PSI and hold a while.

Ok, ty,
Ive been meaning to get back to this...
assuming i am loosing the reference pulse, how do I fix it?
my friend mentioned a chip, but he didnt remember what it was exactly called...

thankyou

If you are loosing the ref pulse it is the ignition module. It sits below the rotor in the distributor. Take it out and take it to an auto parts store and have them test it several times (to get it hot). If it fails, replace it with an AC Delco module, and ONLY an AC Delco module. The other cheap brands are just that, CHEAP. They WILL fail in 4 weeks or less. If you put in a new module it will come with a small packet of thermal grease, use it between the module's metal base and the distributor or the new module will burn out. Use ONLY the thermal grease supplied.
If the module checks good then it could be the wire running from the distributor to the ECM or the ECM itself that is bad.