My 1987 Fifth Ave 318 dies while driving at highway speeds. I pull over and wait 5 minutes and it starts right back up and I can go again for 20 minutes until it does it again. Help

SOURCE: 1996 Camry 100 km stalling

You have one of two very common problems.
Number one may be a stuck open EGR valve
Number two would be a failing Idle Air Control valve (IAC).
Try this: Open the hood & locate the EGR valve, close to the firewall, behind the intake. Find & take with you a small hammer. The next time that it happens, open the hood & tap on the EGR valve. If it is sticking "open" the tapping may dislodge the carbon particles that are keeping it open.When the EGR valve is open, exhaust is getting into the intake at idle, and this will def stall out the car.
There is no repair to the IAC valve, it would need to be replaced if it is bad.
One of these two scenarios will cure your problem, I see it every day.

SOURCE: 1988 honda accord runs for 10-20 min, then loses engine power

Have you checked your alternator?

SOURCE: 2000 s10 Blazer dies very 3-6 weeks for no reason

i would check your ignition system. you would need a meter for this but look for broke or loose connections. if it was a fuel problem i dont think it would just start up after 20 minutes. or you might try your ignition switch. if its shorting or something then ya well it would cut your engine off real quick

SOURCE: 2002 GMC 2500HD 8.1L

Sounds like the cam positioning sensor. I have a 2002 GMC 2500HD 8.1L and this happened to me. Hope this helps.

SOURCE: I have a 1997 chevy

Check for fuel pressure and check for spark during the no start condition. Also check the crank sensor, it is located behind the crank pulley mounted in the engine block on the 4.3 L engine
I hope this helps.