Here is my original thread:
http://www.brickboard.com/RWD/index.htm?id=953436

The problem was that I was getting 4 different OBD codes. Thanks to a few responses, it was determined that the 3-2-1 code is permanently stored in there due to a TSB.

The other codes (2-2-3, 1-2-2, 1-2-1) were not normal. The easiest to tackle was 2-2-3, bad IAC, and it was apparent that it actually was bad. (12V being fed to IAC harness, but no IAC movement/response). I replaced that one with an order from FCPGroton, along with a few other small goodies I had been meaning to get. FCPGroton is awesome! :)

1-2-2 and 1-2-1 were a bad MAP and air temp. sensor. Not good news. However, there were no symptoms. So I did what any other person would have done. I cleared the codes and prayed they did not come back. 1-2-1 came back (bad MAP) but again, no symptoms. I cleared it again. Came back. It was not reappear instantly either. Very random, no pattern as far as I could tell. So I said screw it and reset the code a final time. It has not reappeared yet. I am HOPING that it was a phantom code triggered by a bad IAC, but we will see about that.

The car idles beautifully once again.

Just wanted to update everyone on what was going on and say thanks for all the help. I'll post an update if it turns out the MAP or something else is in fact broken. :)

Oh, and this might be something you want to put in the FAQ regarding the IACs on Regina cars:

Bosch and Regina IACs are NOT interchangeable. According to the FAQ, Bosch IACs have 3 prongs on the harness, whereas Regina IACs only have 2 prongs with a constant 12V supplied to it. I hooked up a multimeter to the IAC lead and as far as I could tell, the 12V is constant, regardless of whether the engine is actually idling, or being revved. This strikes me as sort of odd, because that would seem to indicate that the IAC valve is ALWAYS open, and if that is the case, why even bother having an IAC motor/valve???
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'