88 Buick quits while driving

I have a 1988 buick park with 80K original miles that shuts off while driving at low speeds and turns.
It used to start to run rough then stall.
It would restart and idle in neutral, then stall if I put it in gear.
Now it quits just driving down the road, as if someone turned off the key while driving.
Once my mechanic was working on it when it started to quit and he shot ether down the throttle body and it still quit so it isn't a fuel system issue. I have worked on cars also and it just doesn't feel like a fuel issue.
He has replaced the crank sensor, ign. Control module, computor, power wire to distributor box, and ign coil.
When it starts to quit it is almost like it is reversing the firing order.
I really like this car and it is in exc. Condition. Any help would be awesome. Thanks, Kathy