740 Turbo Sedan stalling out

Fuel injectors can't possibly be dirty enough to make it stall. Does the tach needle drop like a rock when this happens? If so, check the crank angle sensor. If the tach drops with the RPM, the throttle body may be gunked up or the idle control motor could be stuck.

That depends, cutting out can be a number of different issues. Not sure what year this is, but if it's pre-'89 the engine harness might be deteriorating. Could also be fuel pump relay, distributor hall sensor, or in later cars the crank angle sensor instead.

That's interesting. You can pull the whole fuse panel out, at least on the older 700s before they moved it from the center console. Remove the ash tray, remove the pocket above it (screw hidden behind the lighter fascia) and then push on the clips and pull the whole fuse box forward and lift up and the whole mess will come out on a bundle of wires long enough to pull it out of its cave. Look underneath and you can see how everything connects, you might just have a wire coming off a terminal block.

I think to say the electrical systems suck is a bit harsh. They had problems with deteriorating insulation under the hood prior to '88 or '89, but that isn't really Volvos fault, and those Bosch relays leave something to be desired, but for the most part I find them to be pretty dependable once you fix those two issues.

Thanks for all your posts. It is now a month later and I haven't had the stalling-out issue happen any more. Tonight, however, on the way home from work, I think the turbo went out. The needle got into the "zone" where the turbo usually kicks in, but all that happens is a lot of air-flow sound and rumbling and there is no turbo power. What should I do?

Find out which hose ruptured or came off and replace or re-attach it. Your turbocharger is fine.

If the problem is not obvious when you look under the hood, and the car is an automatic, open the hood, firmly engage the parking brake, push firmly on the brake pedal with your left foot, place the transmission in Drive, then have someone stand to the side and watch as you gently push the accelerator until some boost builds up. There will be a tremendous amount of air blasting out from somewhere and that breach is what needs to be fixed.

You shouldn't drive it much like it is, the turbine can overspeed and be damaged with no load on it, not to mention you are letting unfiltered air into the engine.