Volvo 850 stalling after engine gets warm, I can give it gas to keep it on but when I let off it dies.
Things to note:
1994, Non-turbo, Manual, wagon
I recently replaced distributer cap, rotor, spark plug wires, spark plugs, and rpm sensor. The battery was disconnected during the replacement. The current issue was present before I replaced these components but it wasnt nearly as bad.
The radiator fan turns on before the engine dies.
The engine idles fine when cool/cold

 

Hopefully, some of the experts weigh in but I would check the fuel pump. Once I had a fuel pump going out on my 850 that did what you are describing and another time the small fuel line from the pump to the housing insert had become brittle and popped off but was on enough to send some fuel. The car would start and drive for just a bit and then stall. I could turn it off and restart it and it would work for a bit longer. Cut a new little line and it solved it.

Also, check the fuel pump relay. (If you're handy at soldering you can change the caps in them easily which typically fixes them) I had one recently go out on my 850 turbo. It would stall and die after it warmed up. I changed the caps and that solved that.