98' STS Installing Issue/ Advice

Hello, New to the forum, excellent advice here. Here is my issue, I hope someone can help me solve this or had the same issue and can tell me what to do. I have a 98 STS, car runs great. One problem though, in the cold weather when the car is cold too and I start it, it starts fine and will continue to run. After I drive it for a few minutes (5-10min) the car will stall a bunch of times. Once the car has been running for a few and has warmed up it is fine again. There is a small frame when it stalls often. Start the car- doesn't stall (idles a little higher) Few minutes later car stalls at stops 3 -5 times, then when fully warmed doesn't stall again. This happens everday in the cold weather. In the summer/spring months it does not happen. My mechanic can't seem to trace it. No error codes. I do notice that the RPM gauge the idles raises and lowers a little, not steady. Any input or advice?

Since it seems to be directly related to ambient air temps, you might want to consider a faullty Intake Air Temp sensor. Do you have any codes stored?

My mechanic said there where no codes stored, but I think I will check for myself. Is the Intake Air Temp sensor something that I could do myself? I am decent with car maintenance. I noticed that the sensor is only around $13.00. Does it seem like that is what it could be? Thank You very Much for the advice and input.

DFbonnet,
I see no codes, but there are history of codes, would that help to address the issue?

DFbonnet,
I see no codes, but there are history of codes, would that help to address the issue?
Since the problem comes and goes, a relevant code may come up as History not Current. What do you have?
Also, I believe the IAT sensor is under the intake cover. You should be able to access it w/o too much trouble.I have a 4.9 so I'm not really familiar with the Ns.