No idle when cold

Here are the most common causes of idle surge, rough idle esp when cold and stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue 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.

check fuel pressure it could be a dirty inline filter or electric fuel pump thats going bad

Surging idle is usually caused by vacuum leaks. Ford 5.4L engines are notorious for the PCV hose elbow leaking back behind the throttle body.

The PCV tube goes from the right (passenger) side valve cover and loops around behind the valve body. Inspect this hose on BOTH ends.

The choke function is not working on a cold engine.
1 clean throttle body and IAC motor air pathways.
2. Check for engine codes, you are looking for a code that relatws to the wngine temperature sensor.

have a 97 crown vic,
in warm weather it idles fine and run fine
now that its cold I have to hold at high idle to have warm up
for about 10 mins.
if I just start it the engine will die with out me holding on foot on the gas

full power is only achieved when the engine is fully warm(operating temp).so if you accelerate more than, say, a third of the gas pedal,the car will feel sluggish.
this is more apparent when first starting the car in the morning in winter.almost like the car is going to stall.
most wear in the engine is leaving it to idle when cold you should always drive the car straight away from cold.then when hot turn on the a/c if required....

sounds like you have a bad egr valve.

the idle controls could be the problem

Idle air control valve is a common problem Might check that first. Is it throughing a check engine light? with that I can help you further.

I had a power problem, when cold idled just fine,when warm it would miss at idle, spudder on acceleration and sound just fine at higher rpm. found number three spark plug wire had burned through lower boot. Spark was firing to head at low idle. same wire burn twice with about 40000 mile between.