The wife's 93 940 turbo w/ 258k has of late started with a really rough idle in the morning, like it was starving for air or fuel ...but not every initial startup of the day. After running for a spell, it all clears up - even on re-starts. No smell of gas and gets pretty good mileage, so running rich is not in the mix.
Below are the things I found in the FAQ's and doing a search.

Throttle body cleaning.
IAC cleaning
Temp sensor under manifold, checking wire mainly. Not sure how to check proper voltage.
OS sensor?

Am I on track? Any other ideas?

Also of note is that it is a bit hard to start. Pretty sure that is the check valve ..just thought it worth mentioning, even though I had not considered this as a possibility.

Thanks