robert,

I faced a similar problem with my 75 164e. The motor would surge and eventually stall out. It took forever to locate the problem, but once i found it the remedy was simple. The throttle position switch, a potentiometer (black box) located on the side of the air inlet on the intake manifold, had dirty contacts. I simply bought crc electronics cleaner, removed the black cover from the switch, and sprayed the contacts. After working the cleaner in by continually moving the throttle from closed to open (with the engine off of course) the contacts cleaned themselves. Thius solved the problem for me, no more surging or stalling. If you find the contact points are damaged in any way, you might think of replacing the unit. I have not had a manifold pressure regulator fail on me, but i would not rule it out as another possible source for engine failure. Also check your fuel filter,and all vacuum hoses. The mess of hoses by the air inlet is notorious for leaks. Hope that helps!