Cold idle/startup Problem

Hello,

I have a cold idle/startup problem with my 5.8 L '94 Bronco. It has stumped both my favorite mechanic and the Ford mechanics. Upon startup, the Bronco runs fine for 2 or 3 minutes. After this time frame, it will then start idling rough to the point where it will actually die. If you give it some gas during this time frame, the engine will back fire. After 30-45 seconds, the problem clears up and it runs like a champ. If you turn the Bronco off, and restart within 5 or 10 minutes, the problem will not reoccur. If you let it sit for an hour or two and startup, you get the same problem, only it is not as severe. Problem is the worse on complete cold startup... The engine has been tuned up, and fuel injectors have been cleaned of carbon by mechanic and MAP sensor replaced; no effect on problem. During diagonistics, no pertabation observed in fuel pressure, electrical, or any other measureable parameter, even when monitoring during cold startup.... No codes thrown by computer. Both mechanics say wait until problem gets "worse".... Great advise.... Anybody know what might be the problem here?

Engine Coolant Temperature (ECT) sensor maybe?

I would check the ground next to the computer I think in the right kick panel,I think the eec relay is also close. Check in the morning if it clicks when you try to start it. I would check the voltage to your module from the ignition switch in the morning. Put a 12V test light on the ignition coil neg in the morning. Does it blink good when turning over the engine. Put your finger under the egr and check if it moves freely.
If all these check good I would have the module checked free at advanced auto.
I would ohm your temperature sensor in the morning and ask to ohm a new one in the parts store. A big reading I would replace.