So when I start my 1999 f-250 5.4 it starts and then dies immediately.Only when cold. Won't idle no matter how many times I try or hold the RPM's higher.
Once I drive for about 5 minutes it is as if I never had a problem. Runs fine and starts every time with a perfect idle. Just NO COLD IDLE?!!
Any ideas?

 

When you turn the ignition key to ON, the computer is not seeing the cylinder head temperature signal and or the intake air temperature signal to set the fuel rich and open the Intake air controller.
After the motor warms, the Ox sensors control fuel and the motor no longer needs a rich fuel mixture.
What is the motor temperature when you feel it's fully heated?
Does the motor go into high idle at cold start?
Are there any codes set or CEL dash light on?
Could be the intake air controller is sticking closed until the motor warms up.
Or a combination of any above.

 

Something isn't correct somewhere. All these fuel injected engines will start up cold and run well cold, I have never had one fuel injected engine ever not start up when cold or not run well when cold unless there was some issue.(the engine will run at a higher rpm while cold until the engine warms up).

Simplest things first...
1) check your Intake Air Filter, if it is dirty or even if it is not dirty but been in the intake and driven for over a year it May cause a running issue.
2) Pull the air intake boot/hose off the throttle body and spray throttle body cleaner inside the throttle body, all the areas that you can see, to clean it out. It will smoke for a couple minutes when you re-start the engine until it burns all the grime and fluid out. (Mine was filthy, had a thick amount off black grime everywhere inside where I could see).
3) add some Fuel Additive/Cleaner into the gas tank. (for instance, I put Way More in than the directions say and it has never caused a running problem. I personally will put the large 1 Qt. bottle of MMO to a half tank of gas, that is how I do it But, Do your research, I am just saying how I do this, everyone does things differently, usually with he same results though.

Let us know when you have fixed the cold running issue please Sir.

 

So my 1999 Ford F-250 4 X 4 has starting issues. It starts fine but dies immediately, therefore doesn't idle WHEN COLD.
It idles great when hot. If I hold the throttle I can drive but if I let off the gas it dies while driving.
Lastly, if I drive for about 10 minutes, it runs GREAT and it starts and idles GREAT.
Wondering if anyone has some advise or has had this problem in the past?

Phil

 

Most likely a bad IAC.

 

The temp sensor as mentioned above, if it's bad the engine will be really hard to start and keep running , when cold. After getting the engine started and running for awhile all would be fine. That sounds just like the
problem your having,,my bet is the temp sensor. Had'em go bad on me the same way and too add they can also mess with fuel mileage when they are getting bad because of being off on the temp they are reading.