[justa6]

I have exactly the same problem.

Here are a couple of ideas you probably already tried but maybe not.

First, try to set your idle speed as low as feasible. You'll have to adjust your carb(s) mixture as you lower the idle but if you get it lower your car will probably shut off without run on, maybe.

If not then what I do is put the trans (5 speed manual) in 4th or 5th gear and just let the clutch out until it just starts to put a drag on the motor (very slight) turn the key off and the engine will stop immediately, probably. I've got 11.5 to one compression and an idle that will not go below 1000 so I have to use the second method.

Hope that might help.

Regards,