They need to ground the IAC pig tail (passenger side near battery with co2 test point in same harness to set the AMM ) and then set the idle using the bypass valve. set idle to about 650, remove ground and ECU should bring idle to about 750. This assumes they haven't messed with the throttle body adjustments which should be verified.

Of course if they don't know how to ground pigtail for IAC then they certainly didn't know how to set the AMM by attaching a dwell meter to test point and set for an even deflection back and for and then lean towards 40 degrees dwell on meter for slightly rich.(you can use diode method but it is impossible to tell which way to turn to get going or the Volvo tool but for 20.00 a dwell/rpm meter is good for the toolbox anyway) Turn AMM to right to move needle to right turn left to move needle left. It is a very fine adjustment to get the needle to bounce back and forth. May require several turns to get a response.

Good luck, J

ps I doubt the AMM would cause intermittant failure. Even when bad they will go into "limp home" state. Have you resoldered fuel pump relay and the radio suppression relays? They are much more likely to cause intermittant failure.