Car won't stay running

Can you clarify.

Have u checked the cadeletic converter. It can do funny things

Yes, it should. If it is conventional (like other GM cars), the pump will turn on for a couple of seconds when key is turned to on. This will prime the system for starting. When key is turned to start (cranking), the pump is turned on again at the relay, and pump stays on as long as cranking the engine happens. Once engine is started, the oil pressure switch keeps the pump running.
The best way to check if pump is good is to use a fuel pressure gauge. If it does not have a test port called a Schrader valve on the fuel rail, the pressure gauge must be teed in somewhere convenient. But if you take off the line at the filter, some gas should come out with key on, and when cranking the engine gas should come out in a steady stream.

either you have a low pressure fuel,or a clogged fuel filter.

It is not receiving fuel you need to check your fuel pump.

The throttle body needs to be cleaned, grime in this area prevents the throttle plate from closing completely and allowing air to enter, making the air/fuel mixture lean. Make sure to clean the front and back sides of the throttle body. Also, disconnect the battery during the cleaning process to allow the computer to reset and relearn to the cleaned throttle body.

you have spark at the plugs ..thats something

spray stay you mug
into the throttle body see if the motor will cough

tank needs draining and have fresh fuel
fuel pump has a filter and fuel relay

crack the fuel line connection to the rail to see if there is fuel reaching the rail and correct pressure

if sitting 6 years.. not being run regularly
do a compression test
lifters may be stuck
rings may have lost tension

if you can put fuel in throttle body and it runs. then it is not getting any fuel. check your fuel pump fuse and the relay, if ok, then you may have a bad fuel pump or a plugged up fuel filter. check filter and fuses first. good-day !!

After for setting for so long it is possible the pump picked something up and it clogged the injector.

set spark plug to 25th and try that