Just purchased a 1987 Mark VII. The problem is it starts and runs for a short time then quits. The alternator is bad and I have a new one to replace it with. The battery is brand new and fully charged and with start the car after it quits. It has plenty of new gas in the tank. Any ideas?

Can you hear the fuel pump when you turn the car to Accesories?

When was the fuel filter last replaced?

Did you check your MAF sensor? I don't remember if that year was speed density though.

Is the Check Engine on? No? Spend $30 on a cheap code puller, of find a friend with one.

These are things I can think of off the top of my head.

Thanks for the response Digital Oxygen. I have been looking for something like this forum.
The fuel pump is running ok. I adjusted the idle to where it does not fall below 500 rpm and it will stay running. I had to replace both the alternator and regulator but they are working ok now. I will start to slowly go through everything to see what else it wrong, except for the mileage on the car everything seems in fair to good shape. Thanks for now.

How long is a short time? 10 seconds? A minute?

There are many possibilities for this issue. If you just purchased the car my first suggestion would be a standard tune-up. Plugs, wires, cap, rotor, air filter, fuel filter, transmission fluid, brass TV grommet, coolant, oil, oil filter, pcv valve, brake fluid flush, thermostat. I would also adjust the TPS, use a 180º thermostat, run some seafoam through the intake and gas tank, and bump the timing to ~12º. This will help to make sure that the engine is in better tune for troubleshooting.

From there, pull engine codes. A $25 code reader is a worthwhile investment. If you are stuck on not spending the cash for such a useful tool it is possible to gather the codes with a test light, or even a paper clip. Regardless, see what the computer tells you and clean up from there.

As for your specific issue, it sounds like you have it resolved with adjusting the idle, correct? If you have a surging idle, you may get a code 34 for the EGR or something similar. Cleaning the IAC and EGR may help with your stalling issue. Throw me some more information, especially codes, and I am sure I can help you more specifically.

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1989 Mark VII Bullitt. Shaved trim, emblems, antenna, trunk latch cover, and door handles. Blacked out with 100% custom interior and 35% tint. 17" Bullitt rims wrapped in BFG 245/50R17's. 1800watts of custom audio. Completed over the course of six weeks.

You gave a telling piece of info.
""Adjusting the idle to 500 rpm and it keeps the engine running.""

This tells me the IAC is frozen and not conrolling the idle speed.
What you did by adjusting the stop is take the place of the IAC and admitted air by stop adjustment.
When all is right you do not want the stop adjusted upward to control the idle. That is the job of the IAC controller.
There may be other problems before you get it all straightened out in addition.

A reference was made to the fuel pump running in acc position; it only runs the pump for a second or two in 'run' position not in acc position.
To explain this, when the EEC is powered up it starts a timer that grounds the pump relay for a short time. When the engine cranks over, the PIP in the dist pulses the EEC, restarts the pump and keep pulsing the timer and keep the pump running as long as the engine is turning over.

You are correct. I was thinking of Accessories Position, though I knew it was Run position.