Engine dies on deceleration

I have a 1983 320i. It had sat for quite some time and had a number of parts stolen from it. I think I have replaced most of the parts. There is one 1/4 inch hose from the bottom of the intake manifold that is stubbed off and I haven't figured out what it went to.

The engine idles nicely (a little high) and runs well on the rode; but when I decelerate either by mechanical braking (foot or emergency) or engine breaking, the engine dies. If I punch the accelerator a bit, it usually recovers and idles normally. If I park nose down on a sharp incline, it is very difficult to start. It starts very easily otherwise. The milage seems to be good (about 28 MPG). If I coast to a stop or decelerate 'very' slowly, it will run fine.

The engine idle is a little high (1500 RPM) and a bit rough. I've tried to set the idle lower, but it get rougher. I've adjusted the fuel sensor plate (it was touching the side and set lower in the venturi than speified), accelerator cable and butterfly valve, replaced the fuel distributor because the plunger was worn and sticky and the new one moves smoothly.

I notice a 'safety switch' under the sensor plate in one of the manuals with no explaination about what it does.

Does the '83 320i have an inertia switch to cut fuel off that might be overly sensitive?

I have tried everything I can think of. Does anyone have an idea? Thanks

PS Since I posted this, I have attached a fuel pressure gauge to the fuel distributor inlet. The pressure maxes my gauge at 60 PSI. It does not change when the engine dies until about 30 seconds later. Probably normal. :-)