Sounds to me like the fuel injection on cold start up fuse has been removed, If you keep your foot on the throttle the engine will continue to run, remove your foot from the pedal before the engine can warm up the engine will die.
If you allow the engine to warm up the engine will stay running.

An easy check for this fault is to check the heated seat fuse. Many people remove said fuse because the MK4 Escort never had Heated seats, Ford just used the parts bin for the fuse box lid.

 

20 amp fuse? from (very distant memory)

 

 

Now retired at 75, was involved back in the day with all aspects of the "Bosch" "K" & "KE" systems, the fact as you say the engine bursts into life right away tells me your only running on the Fuel spray from the 5th injector, may I ask if you continue to try...does it eventualy run...but difficult to keep going till it warms up a little...ie..touch the throttle..and it stops again ?. this then points to the Pressure actuator not working and not increasing Fuel pressure for the cold start up, but once you get it running all fine, need to know this...wont go into more at moment, but can give ALL tests for Pressure actuator. Peter.

 

 

Just say the Injection ECU [ black] has to have live 12v on pin "1" of the 25 pins, to identify pin 1....you will see a longer line of pins....ie...1 to 13 and a shorter line 14 to 25...so pin 1 right up the end [ sorry cant remember which end ]. Remember the "Bosch KE" system will run without the supply to pin "1"...but will be a nightmare to start from Cold, as the ECU keeps control of the IMPOTANT Pressure actuator etc, ECU has NO control of the Fuel Pump / Relay / fast idle valve/ or Cold start 5th injector, hence car bursts into life.

 

 

The pressure of all "K" & "KE" systems is the Pump maintains 85 / 90 psi all the time in the system , of course at idle the pressure is 35/40 psi, increasing pressure as to more throttle / power used, at the Fuel pressure control unit, so you need quality replacement Pipe capable of "90 plus "psi" most is these days from Motor Factors.

 

Those pipes are standard fitment, They are held on by spring circlips. I replaced mine, just because they looked tatty after the braid started to fray.

Does it look like they have been touched recently as they could have been swapped over by accident.(assuming you havent just bought the car)

 

 

Your correct the engine would not run at all with pipes mixed up, I refer to my first write up your running on the 5th injector only....hence bursts into life...but only on the fuel from the 5th, do Test there is a 12v supply to Pin 1 on ECU, also while there check Pin 2 is earth..ie..negative, 2 esentual circuits for ECU, BUT before doing above check the "Coolent Temp sensor" yellow plug, under the intake manifold is fully secure..no broken wires / clean connection, as this is the only way the ECU knows to increase pressure to all 4 injectors via the pressure Actuator, if all perfect make sure the Pressure actuator located on the metering head towards the front, that the 2 pin plug is secure / clean. There is a Full Test hear that I can explain, but one must have good knowledge of use of multimeter and ohms testing.

 

If the coolant temp sensor were open circuit the fuel ecu would default to -55 C as it is not very bright

 

Just sounds like a vacuum leak to me, check all your hoses are secure and not split.
Hold the flap down a little under your air filter whilst someone else starts her up, if it runs whilst held down a little then it's 99% an vacuum leak.