that sounds like your AMM went, and your car reverted into 'limp home' mode.

From the FAQ:

"Poor Driveability: Bad Air Mass Meter Symptoms.
"Limp-Home" Mode:
[Would someone give me give me a description of what a bad AMM feels like?] My single experience with a bad AMM was that the engine would barely run at all and was not driveable. I think it reverts to "limp home mode" if you pull the connector off. But I still think you should clean the throttle body. Since the purpose of an AMM is to regulate air flow to the throttle body, it usually sits right on top of the air cleaner or close by and there is some sort of connector on it. Remove the connector and see how your engine runs. It should run like crap, i.e. no power, idle fluctuates wildly, or engine stalls. If this is similar to the problems you're experiencing now, chances are that the AMM is bad. Another thing to check is that there aren't any air leaks between your AMM and the throttle body.
Connector Problems:
More than one inexperienced technician has failed to cure an intermittent driveability problem by replacing the mass airflow sensor. Even if your pinpoint tests suggest a failing sensor, always inspect the sensor's harness connector for loose terminals first. Be sure all the terminals are locked securely inside the connector before you condemn the mass airflow sensor. Some routinely remove a harness connector and then reinstall it to see if "reseating" the connector solves the car's problem. But reseating the connector on this Bosch airflow sensor may complicate diagnosis by pushing the loose terminal outward. So, your quick-fix trick actually makes the car run worse than before! Also, try cleaning and de-oxidizing the connector before reinstalling it.

Disintegrating Air Box Foam:
[Tip from Chris de Courcy-Bower] Check the air mass detector. This can be defeated or even damaged by bits of disintegrating foam rubber that break away from the upper casing of the air filter box. As the foam rubber seems to serve no purpose, it is my recommendation that owners remove every trace of it before it causes a failure."
--
Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'