You should find another Mechanic, Volvos are still internal combustion engines and any Mechanic worth his salt should be able to perform basic diagnostics.

You really don't want someone doing "misdemeanor parts throwing" on your dime!

#1 check the vacuum hose to fuel pressure regulator for gas,may be dumping fuel into the intake. CTS failure is another possibility. Gas mileage down?

#2 Timing belt may have jumped retarding both valve and ignition timing. Timing belt old?

#3 Possible Hall sensor failing intermitantly. Mine acted that way,0-2000 RPM's

#4 Buy a Vacuum gauge and a timing light. About the best you can do without OBD.

#5 Tons of good info in the FAQ's and do a search on "stalling".

Good luck!