1991chevy lumina starts hard, runs sluggish and then dies when put into drive. already replaced computer

Mass air flow , crank sensor . I wouldn't discount anything . Having a scan tool that can view engine sensor data would be a great help too , testing fuel pressure and flow and back pressure test the exhaust .
058 Engine Hard to Start or No Start Lean Fuel Condition
055 Engine Hard to Start or No Start Scan Data for EGR
057 Engine Hard to Start or No Start Ignition Module Test
007 Catalytic Converter Testing

On electronic fuel injection pumping an pumping an pumping the gas pedal does nothing without the engine running ! Pushing the gas pedal to the floor will cause the PCM - engine computer to go into clear flood mode .

You have some very interesting ideas here , but not really how it works or is !

The vehicle will go into closed loop fuel control when the engine coolant temp reaches a definded temp an the O2 sensor get hot.

She would run for a couple minutes and die which is open loop when running, closed loop is when the sensors kick and it would die. Pulled spark plugs, they were black meaning no spark. Can only be 2

Black spark plugs indecate a rich condition , over fueled , wet spark plugs indecate no spark .

check fuel pressure most likely bad fuel pump. also check your oil sending unit or gauge. chevys run the fuel relay to the oil pressure switch in case the oil is so low the car wont start. sometimes the relay in between this circuit goes bad as well. if all is well check or replace the ignition module (located directly under coils) or distributor integrated if it has a distributor

I just recently have been fighting the same problem with the same make/model/year vehicle. For myself, I would drive off and on through the day and it would run fine. Then suddenly after a start it would run rough and die. I would have to wait 20 to 60 mins before it would start again. I had it checked and fuel pump was only putting out around 19 psi. It should be around 41 psi. Had fuel pump replaced and no more problems. Furthermore, now it runs so much better. It's funny how over time I didn't notice how the performance was slowly degrading. Unfortunaley fuel pumps for this car run around $300.

check fuel presure

did you gap them properly? did you replace wires too or just plugs? You may have a bad wire. To test wires, simply start the car and pull the wire off the plug and put it close to a metal object on the car and if it sparks then the wire is useable. An irregular pattern means to replace the wires.

I didnt see it in your list, so I would suggest the O2 sensor, usally found on the exhuast pipe near the engine or on the back of the engine

Sonds like a sensor putting out an error code to shut it down ( like a fatal error code) Prolonged vibrations and heat can make cam sensors, maf, o2 senosr do craz ythings which will actuate a govener and stall your car...could also be you fuel pump causually telling you that "hey im bout to die".I dealership can run a stress test (if you will) to check the longivity of the pump...
Good luck hope this helps :)

Hi,

Sounds like the ignition coil is getting bad it gets hot and stops working and when it cools off it works again. I would replace it and your problem should be solved.

if you can check for spark when it wont start and fuel pressure and the service port , would be great information , otherwise pattern failure is ignition module and crank sensor (replace them as a set) , after cools off it will run again.