Try a higher octane gas and see if that helps Your engine may be getting too hot. Check to see if your radiator fan comes on. or Take your Ignition Module to an autozone and have it tested.
CHECK COIL PACKS
If the check engine light is on...might be a dirty EGR valve.
it could be vapor lock
When driving the IAC does not do anything because the car is not at an idle
cam position sensor has failed
There are several things that can cause your 1990 Volvo 740 to stall while driving. The most common cause is a bad fuel pump.
crankshaft position censor
There are several things which could be causing the car to stall out while driving. The most common and least difficult problem is that the spark plugs may need to be changed.
It could.
A dodge pickup 1500 would stall out while driving because of a defective air filter.
If it is the 7.3L diesel .I would check the crank sensor.
main fuel relay going bad. Eventually car will cut off while driving.