450SL stalling problem

[Toddski]

Well I'm baffled. I have a 73 450SL 107 that I've been through pretty thoroughly over the years. It's been in the family since new and I'm the third generation to work on it. Over the past few years I've replaced a few sensors, the intake manifold gaskets (twice), timing chain, fuel pump, interior carpet and center console, speedometer and clock, disassembled, cleaned, painted and reassembled the entire fuel injection system, plugs, cap, rotor, wires, coil, battery, and a thorough brake job. About the only ignition part I haven't replaced is the distributor points but they look fine. So here's my problem: the car runs great, starts right up, warms up, idles smooth, jumps up on the freeway, pulls hard and solid, just a joy to drive for about 45 minutes. But then suddenly, it's as if I turned off the ignition switch. Even at 80mph, I will suddenly be coasting and desperately looking for an offramp! I THINK it's an ignition problem but by the time the tow truck gets it back home, it starts right up and drives smoothly back into the garage! So how to diagnose this problem that occurs only at remote locations far from my garage or any mechanic? Any thoughts? PS, Phil rocked. Always there for me like I was the only customer he had. RIP Brother.