I have already replaced the fuel pump and filter, also the ignition module, distributor parts, plug wires, plugs and coil.
Driving uphill, at approx 7000 elevation or higher, the engine stops and the panel lights come on. The symptoms are very similar to vapor lock on a carb vehicle. After about 15 minutes it starts and runs fine. Never has stopped below this altitude or on the flat after topping out at 8.6k feet. At first I thought it was a temperature problem occurring only when the temp is over 90 degrees, but temperature does not seem to matter anymore.
Any ideas on what is happening?
Does a 1986 740GLE have more than one fuel pump?
How can I, quickly, diagnose if this is a fuel or ignition problem on the road?
(This road is fairly busy and has no shoulders!)

hi ya this is tom, i had a 86 240 that did the same thing i was going nuts.i replaced just about every thing that i could think of then one day a volvo master mach.told me that the controll mog.is at falt becase the pins wear down and neds new spacers pins.well i put in a newer mog. and that did the trick no more dieing car.well the car was hit by a drunk driver but i saved all of the best parts in it if u want the controll mog i will sell it to u verry cheep.i have lots of good parts.oh yea the controll mog is that big black box that is next to your washer tank. :banana: and it could be your fuel pump realy to i have a brand new one too