1994 4.0 ranger truck idles fine for a few minutes then comes bad /rough idle along with check engine light.If you turn off truck and try to restart it wont start and fuel pump runs continously.if you turn the switch off /on numerous times fuel pump will stop truck will then start

If it runs fine and the idle is the only problem you could try idling it up some with the idle set screw on the throttle body it sounds like it may be a little bit out of time those toyotas have a fine lins on the timing.

IT SOUNDS LIKE THE IAC (IDLE AIR CONTROL) MOTOR IS BAD OR GOING BAD, BUT THE QUICK SOLUTION IS GO TO ANY AUTO ZONE,OR ADVANCE AUTO PARTS STORE, AND THEY WILL CHECK IT FOR FREE,& TELL YOU WHAT SIGNAL CODE MADE THE CHECK ENGINE LIGHT COME ON, I WOULD DO THAT JUST TO BE FOR SURE, BECAUSE THERE ARE A FEW OTHER THINGS THAT CAN CAUSE IT AS WELL,SUCH AS MAF SENSOR DIRTY,OXY SENSOR GETTING A BAD READING,ETC.

i would check the egr valve first and then the fuel pressure regulator or the idle air control valve

You might have a bad coil. Under a load the coil might preform well, but under no load, its weak causing a misfire...thus giving you a rough idle. I have had this problem on a few vehicle. Check plugs, wires, and distributor. Mike.

sticking valves. the short run of the engine free's them enough to enable runnig

check the throttle body inside .
look and see if its all black around the butterfly inside there.
thats the throttle thing that opens and closes with the gas ped being pressed.
if its all caked up around the plate then spray it clean and wipe with a clean rag it should be nice and clean in there and then change to super unleaded fuel only.put a obd2 comp on the car and give me the codes so i can help you further.autozone can get and give you the codes for free.

there are 2 things that usually cause this, one is a dirty intake idle control valve and the other is hard engine mounts, I would say that both most likely apply to your car. try cleaning the intake with the following procedure from Ford.
Here is the most common cause of surges and stalls and low idle rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Just trowing some suggestions out there, but, I would check the idle air control valve (solenoid) or the throttle position sensor. If they check out then my last guess would be the map sensor or the vaccuum to the map sensor. Hope I was able to help. Best wishes.

Check the fan it is not running,

your head check for burnt or damaged valves. or spark control