Vapor lock or in-tank fuel pump are good possibilties.

Does your car have an in-tank fuel pump and a main pump? My 90 240 had both. Don't know about 740's. The in-tank pump might be dying. The main pumps on Volvos usually go a long way. Can outlast the car. My 90 when I sold it at 300k still had its main pump. My 850 has just one pump and it is still going strong at 200k! Fingers crossed...:)

How full is your gas tank?

Try filling up.

740 fuel pick-ups have problems as they age.

Our '88 745 GLE acted up when fuel got below 1/4 of a tank. We owned this car so long that we forgot twice!

I have read posts that told of this problem getting worse over time.
--
'96 855R,'64 PV544 driver, '67 P1800 basket case, '12 XC70, the first three are mine, heh, heh, 525,000 miles put on 10 bricks

Dies and restarts when cool is not quite enough information. But there are two very common temp related failures: FI system relay (formerly known as fuel pump relay) and the ignition power stage.

If it is the FI relay you can open up the relay tray, pull the cover off the relay. Turn off the radio and leave the fan on a nice quiet setting. When you hear the relay click, have a passenger push the contacts back together...On 760, this was usually enough to finish a drive in peace. In my case it was not the relay on my 1990 760 turbo but the relay socket but to the same effect...the heavy lugs could carry current but the coil would open and close intermittently.

If itis the power stage, about the only thing you can do in the middle of the desert is try to find new dielectric grease at parts store and re-grease the back until you can get the proper paste.