My 89, well maintained 760 Turbo (270,000 K) has stalled several times over the last few months, but only when the wife was driving (Murphy's law).

Conditions:
- Usually when motor is a little warmer, after about 10 to 30 minutes of driving

- stalls usually at steady speed

- Engine always misses a few times, intermittently first, and then completely stalls - competely dies while at speed

- Electrical still works

- Sometimes pumping gas helps to get it started, but usually, when it needs that, it will die again anyway - when it does start fine, off she goes again!

- this last time, it took half an hour to restart (wifey walked away and came back a few times)

Once it starts, it runs fine again, often for a few hundred Kilometers. Smooth and silky like always (until it dies again - can't predict when).

Car is well maintained and has newish plugs (6 months old), no bad gas, Scope diagnosis says all is working fine.

We haven't been able to test the car when the problem is occuring - only when it is running fine. All mechanics say they need to be there when it dies to catch it in the act - $$$$$$

One mechanic spotted a distributor problem and fixed that thinking it was the fault - nope - 300 K's later, the car stalled again, and wouldn't start for 20 minutes!

Next step is I'm changing Fuel Pump Relay.

Not sure if original Fuel pump is still in car (I bought car at 200,000K)

From these forums I've got the following additional suspects:
Fuel Pressure Regulator
Fuel Pump
Fuel Ignition Relay
Ignition Power Stage amplifier
Overboost switch

Any/all suggestions greatly appreciated!