There are quite a few tests that you can do with the little plug box in the engine compartment - I know because I tried them all on our '90 744 Tl.

Turns out my computer was gone.

At my pick and pull, a Volvo specialist, they had about 200 of them for NA engines - about $100 each. For turbos, they had none, and could not find me one.

Hope that the belt is gone, or some other simple cause is the problem, as a new computer was $720 ten years ago.

BTW I did change the crank position sensor three times in 75K miles. Did you put in a new one, or how did you check the old one? To me this is a very common cause of failure.

The only other problem I ever had with the car was bad grounds in the left front fender. This caused it to stall when the high beams were used - the headlights steal all the ground available. This is in the FAQ!

Check and clean all the grounds in the left front fender area, including the mounting of the power stage as was mentioned, I think that there are a couple that are not evident, like at the mounting of the anti-lock brake box. Also check the two small wires attached to the positive battery terminal, one of mine was so corroded that I could pull it apart. I stripped the wires, trimmed then and soldered them for a good connection.