[Arnoldtheskier]

Pcv,elbow,booster diaphragm, as mentioned.

I would go back a bit.

Put the old pcm.,iac, back in.
I would be looking around at the wiring. Do a wiggle test..with the car off/running. While scanning. lol..lots of stuff has shown up during this!

Fuel pressure and volume test.

Failing the above. I had an idle issue that I could not fix. I had to make an idle speed adapter with a bracket. Fixed that problem and drove the car for a year or two..even through E test. Never did find the problem. You can do this with another throttle body.

Run it through an etest,eg gas test. That can often nail down where the problem is by the eg gas readings. Ideally..some pro's start the car cold

My guess is that it is in the fuel rail/injectors. And affected the cold start set up.

A bad fuel line/filter can bring grief.

Some of the newer "real time" scanners are pretty cheap now. As well as being very powerful and sophisticated..lol Drive the thing and they hold a ton of info that can be upoaded too! Read the codes,record them,clear the codes,have at it. I never said to watch it while driving to see when it occurred.