Dear kaeoflux,

Hope you're well. The stuttering and shaking likely meant there was a mis-fire, which was cured by new distributor cap, rotor, and plug wires. One or more of those items - likely all factory-original - was simply worn-out. The distributor cap and rotor should have been made by Bosch (the supplier to Volvo). The plug wires should say Volvo or Bougicord (the supplier to Volvo).

As to the stalling, that's most likely due to a failing ignition power stage. This device is mounted against the inner fender wall, in the engine bay, just behind the headlmap. I believe that on turbo models, it is just behind the passenger headlamp. The power stage is flat, with a gray "cap" and mounted to an aluminum base.

Another possibility, is that the ground - to the fuel injection relay - needs to be cleaned. The ground points in the engine bay are also affixed to the inner fender wall, just behind the headlamps.

The corrosion need not be visible, to disrupt the circuit. Sometimes, a layer of corrosion only a few atoms thick (and so invisible) will stop the flow of power.

There are aerosol corrosion removers. You can also clean the ground tabs with fine steel wool or fine sand paper.

It is a good idea to consult this site's FAQs for a list of things to be replaced, when one acquires a car, without maintenance records. For example, if the radiator is the factory-original model, it is long past the end of its service life. When it fails - usually a host nipple will crack/break - all coolant is lost in a minute or so and severe over-heating results.

Hope this helps.

Yours faithfully,

Spook