Engine stalls. engine runs good even when idling.but sometimes engine just stops while running.try to start engine but wont start.starter working fine.after 5 mins engine will start again.i also hear constant humming from the fuel pump.

There are several possibilities for this problem. A "cold start" sequence is suppose to activate based on water temperature and the signal from the water temperature sensor. This makes the fuel rich and adjusts timing to make the engine run better when cold. It works like a choke only it is electronic.

There may be 2 sensors with one making the dash gauges work and the other doing the engine controls. If not 2, then 1 sensor would do the whole job.

Another possibility is an air leak in the fuel system which makes the system bleed dry overnight. It is far less common on gas engines but happens a lot on diesels.

Some earlier Ford engines from 1984 to I don't know when they stopped on trucks, would use a step-up solenoid on the accelerator bracket that worked off water temperature. Sometimes a bad water thermostat would make the temperature controls malfunction the other way (High idle, clicking, low idle) that would stall and engine as the temperature vary.

Engine stalling and rough run issue at low speeds

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

when you removed the water pump, did you disturb the timing in anyway ???

soundl like idle air control valve sensor
try a clean .............if no better replace

sounds like the idle control vale is sticking when it is cold. It is located on the throttlebody right at the air inlet

Check your fuel pump presure. Pump is in the tank. Also try and loosen the fuel cap, the tank vent may be stopped up.

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.

hello first check your idle with the car running foot on brake see were your rpm reading is if your below 500rpm check your label underhood for your curb idle setting second see if theres a adjustment screw you can increase were your gas cable lever rest against your set screw underhood if you feel confident enough remove your iac motor idle air control valve if the bore were the end of the pintle extracts out to close has varnish builup our carbon it will stick creating vacuum leak type senario causing stalling rough idle sometimes even no start conditions good luck

it sounds to me that you idle controll valve isnt responding (could be dirty) get a can of carb cleaner and clean the thottle body inside and with the engine running. squirt just a little and the engine will start to stall and the idle air controll will start to open ( you will hear it start sucking) then spray more in sperts try to keep the engine running at idle . this will make the engine RPM's change and open and close the idle controll valve thus cleaning it. when done save some carb spray. put the air cleaner hose back on. and start the engine and with the engine idling spray around the intake and base of throttle body if the rpms change you have a vaccume leak than will need to be repaired.
good luck
tech rating 3

your on the right route but also check egr valve