Hi Diane, please look at the 700/900 FAQ via the 'features' pull down menu. There is a lot of info there from previous posts here and elsewhere.

Your problem may be caused by some electrical ground problems, ie dirty contacts, or a dirty throttle body. Pull off the intake hose, from the air cleaner to the throttle body, and loo at the inside of the TB. Open the flap and look inside with a light. There are various small vacuum hoses attached to the TB and the small ports may be blocked with oil crud.

You might also check the Air Mass Meter, connected to the air cleaner with an electrical connector attached. Make sure the connector is clean and properly seated.

Then there is the fuel pump relay. A quick resolder job on it may cure your problem. This relay supplies, on my year and probably yours too, power to the fuel pump and the AMM.

Check the 700/900 FAQ for more info on this. There si also a section on buying a high mileage Volvo, although 100K is 'broken in' around here.

You must make sure the timing belt was changed at 100K miles too.