why does my 1983 vanagon stall while driving and sometimes not start?

What is your question?

This is very intermittant, but I have been stranded numerous times while driving. the car feels odd, and begins to lurch like it is choking then eventually stalls. If I park and wait about 25 min it will usually start up. I have to really crank the ignition when that happens. Most of the time it starts right up, but then out of the blue it won't start and I have to wait 20 min and crank it. it sounds like i am running down the battery, but at the crucial moment it catches. my mechanic will only deal with it if he gets it acting out... so I'm on my own praying not to stall on the road.