Is a better quick test to check the TPS to do is with KOEO turn the throttle and listen for the clicking noise? Instead of with engine on.

Also this is an intermittent problem. The car runs great, except when its not.
(thanks yogi). Then every once in a while this rough idle, almost stalling occurs. If you put the car in park and let the car run a while it seems to go away on its own.

My daughter drove the car this evening and it stalled out a block away. she was able to pull over to a side road sit a while the car restarted and drove fine, she came back and took my 2005-S40 instead. I went out and restarted car and it started and idled fine. Seems like it happens at a cold start only.

The other thing recently I discovered for a rough idle that was a simple fix- The COIL WIRE was arcing to the power steering hose metal connector. I relocated the wire and the rough idle went away. I looked in the engine compartment in the dark to see if I could see any arcing tonight and did not see any. I did not see any vacuum hoses unplugged or damaged.

This is becoming a safety concern.

The other point is that parts are not as expensive as they used to be. The MAF had not been changed in a while, The IAC was changed because my 95 850 GLT had rough idle problems and replacing the IAC corrected it)

The throttle body was definitely dirty including the little vacuum ports (they were completely clogged. This was cleaned with TB cleaner and a new gasket.

I did not replace the TPS because I read it needed to be calibrated when installed and I do not have diagnostic scanner.

I did check the codes and had a 3-2-2, and with ignition something for a wire for the MAF. _ I cleared the codes after replacing the parts and cleaning TB and no new codes came up. I had 1-1-1 on ignition and fuel.
thanks