1991 ford van

Likely a gas or spark problem. Spray starting fluid into the air intake while cranking it. If it then runs for a few seconds, it's a fuel problem-maybe the fuel pump, filter, or injector circuit. Check if gas is getting up to the engine.
Buy an inexpensive "spark tester" at a parts store, and check for spark- if no spark, the ignition circuit will need diagnosed- could be the ignition coil, maybe the electronic ignition module-several possibi9lities. Let me know what you find, or if other questions..

purge valve is just that a valve it puts access fuel vapors back into the combustion chamber for the engine to continue to burn them. there is no filter on it however it could be bad and causing the rough idle

Thanks for using FixYa and welcome to the site Clay. It could be either one of them. The only thing, there are many things that can cause this. Have you checked the fuel pressure? Could be a leaking injector. You could have a vacuum leak. It may be a MAP sensor, the Idle sensor, or the EGR. All of them are possible. What was your codes? I see the numbers but what is the detail?

Well if you ran out of fuel that means the pump sucked lot of air in, and it wil take o while for the pump to deliver the fuel back again to the injectors. and if its a diesle, you might need to purge it.

On a 1991 Ford Thunderbird with a 5.0 V8, the fuel filter is on the bottom of the passenger floorboard just behind the front wheel. Turn the car on and open the trunk. Behind the carpet on the drivers side of the trunk, there is an inertial fuel cut-off switch. This is triggered if/when the car flips over or hits something really hard. Disengage this cut-off while the car is running. It will lower the pressure in the fuel line and the engine will die. Disconnect the battery under the hood. The fuel filter has a splash guard covering it. Remove the two bolts and un-fasten the quick-connects on either side of the filter. Save the two clips unless the new filter came with new ones. Remove the old filter put the new filter on and replace the retaining clips and the shield. Connect the battery, engage the inertial switch, and start 'er up. Should turn over for quite a few seconds until the fuel fills the filter and lines.

there is a relay for the fuel pump beside the air filter on my 91 f150 4x4 4.9L i6 300 I am having having problems with fuel pump also. hope this helps!

could be torque convertor valve or sticking valve in transmition, best get mechanic to check it out

fuel level to low,air in fuel system,idle adjustment incorrect,fuel feed or return blocked,air intake/system blockage,blockage in exhaust system or faulty injectors. Hope this helps

If you put a scanner on it and you have no misfire codes I would be looking at either an egr valve stuck open a little or a bad Idle Air Control Valve

The EVAPORATIVE PURGE CONTROL VALVE is located under the hood usually behind or near the back of the headlights. It it on the top of the Evap Charcol Cannister ( shaped something like a Quaker Oats box ) . Basically does not allow fuel vapors to escape into the air. Te purge valve will recycle the vapors through a charcol filter and sent to be reused as fuel., Problem could be caused by excessive fuel in the cannister, or the solenoid, or wiring, etc back to the computer.. Requires a lot of diagnosing. Hope this helps.