hello fellow volvo fans ....i am having troble with my 85 740 ...that has been owned by my mother since new...

car had been sitting for some time after stalling on the highway last year

after stalling it would not start up .. i had it towed home and i tried to start it up 2 days later ... it started up fine but ran a little rough ... it then sat for 6 months ... when i recently tried to start it up (last week) it would not turn over ..i then checked the plugs ..they where black (somewhat fouled i guess) i have replaced them ..after replacing the plugs and charging the battery she started up no problem .....while taking a test drive that same day she stalled on me again ...and would not restart

after sitting for aprox 10-15 mins she turned over quick ..then 1-2 minutes into driving she stalled again ...again car would not start ...i let her sit for another 10 mins and she started no problem... this then happened the same way 2 more times untill i finally got her home... where i let her idle in my driveway
5-10 mins later she finally stalled while idling.....

please help i dont know where to start????

Jack