Hi i got a 94 850 turbo i was driving one day i have automatic so i pressed sport mode to pass someone i went from 35 to 55 then a loud pop bang whatever you call it came and i felt no power at all it will not go past 35.... when i start it.. it starts fine runs fine until 20mph also you can hear the turbo spool but its like the turbo goes but the motor will not keep up with it... i have check lights pop up with a cylinder misfire but that was popping up before this happened i was going to take care of that next day then this happened any suggestions

SOURCE: starting in damp weather 1993 240 wagon, auto/od, 235k miles

perhaps you need a new cap and roter a new spark plug wire set. they don;t like moisture. also check to see if you have any broken or leaking vacuum hoses. the worse case senerio would be that your head gasket is leaking--at cold temps a little antifreeze will enter until everything warms up and it seals shut due to metal expanding. but since you say it's cold weather only--this probably wou;dn't be the case. good luck.

SOURCE: 1988 volvo 740 gle non-turbo loud fuel pump

Have you tried replacing the fuel filter? It is located under the cars center on the left side ..

You will find it alongside the main high pressure fuel pump on a metal support plate held up with 3 bolts.
Remove the 3 bolts with a 10mm socket wrench to lower the plate. Place a catch pan below the filter to catch any leaking fuel.
Be careful not to get fuel in you eyes or running down your arms. Remove the 2 bolts holding the banjo fuel pipe connections to the filter.
Note the direction of the filter.
Loosen the clamp holding the filter to the support plate and slide out the old filter.
Install the new filter in the same direction as the old one and use new copper sealing washers on the banjo connections.

SOURCE: 91 volvo stalls at anytime

TRY ANOTHER FUEL PUMP AND FUEL FILTHER THESE PUMPS ARE FUNNY ON VOLVOS HAD SAME PROBLEM ON 850 TURBO AND SURE ENOUGG IT WAS THE PUMP

SOURCE: engine splutters and dies when i try to turn it on

Same problem on our 2001. Replace the fuel pressure regulator.

SOURCE: ENGINE MISFIRE AND SHAKING

check your wire harness on the top of the engine. Volvo must have bought harnesses from Mercedes. The insulation just cracks and disintegrates, then the wires short. Not good for an ignition system.Once they short It can fry the circuit for that cylinder in the computer. Does not set a code other than Misfire.