I have a similar problem with my 2000 explorer 4L SOHC
ford replaced the iac which didn't help, had it back the 3rd time now and they told me they don't have a fix. even ford motor don't know what's the matter, it's been at the dealer for 1 week now.
but, of course I don't know if we have the same problem, all I can tell you, keep taking it back every week or, if you cant get it fixed, start calling ford customer service.
Test your ECT, engine coolent temp sensor. It controls 3 things for a cold start; the EGR, ignition timing and fuel mixture. This is the first place I would look.
Im not sure what the IAC is. Intake air control? Is this the air intake temperature sensor mounted in the intake manifold? If so, it helps compute air volume for fuel mixture, but does not affect the EGR operation and timing during cold engine operation.
It you remove it, they recommend to replace it instead of reinstalling it because it can crack the ceramic and you may not know it.
I have a '96 that does that when the outside temp drops below 35F. If it was cold (under 35F) during the night and I start it later in the day, say at 45F or more, it was still hard to start. But if the night temps stays above 35F, it would start up in the morning without problems. I'm leaving it alone, if the problem occurs anytime after it warms up (say, in Spring) then I will have it serviced. I think its just the cold temps. Also, it only did the hard start once a day, after the first hard start it worked just fine! Good luck!
I am looking at replacing my 93 Aerostar AWD (116K miles) with a newer Explorer in the future. With all the complaints I am not so sure. Our 4.0 V6 has been cranking & running ok at 15 below and a minus 35 chill factor in Nebraska. The cold is tough on a displaced Mississippi Boy. I would check out the temp coolant sensor as they do cause problems up here.
93 Aerostar AWD
92 F150 XLT ext cab
89 bronco II XLT