I apologize if this topic already exists and if it does, I was not able to find it.

I have a 99 Explorer XLT. Issue: in the winter time when I start it up first thing in the morning, it starts but a few seconds later idles low and stalls. I have to keep my foot on the gas for a few minutes, after which it runs fine for the rest of the day.
When the outside temperature is above +4, it usually does not stall, but it struggles to idle properly. Several minutes later it runs just fine.

I've been having this issue for over two years now. My mechanic is not able to figure it out.
Recently there seems to be a pattern (could be due to warmer weather), it has a bit of a difficulty idling in the mornings and that’s it. However, before it was very unpredictable. It would stall at random times, with no warning.
So far I have done the following: replaced the IAC, cleaned the injectors, and replaced the relays responsible for idle functions.
Has anyone had a similar problem and have you been able to find a solution?

Thanks.