Latest post of the previous page:
sounds like you have looked at the setup carefully. If the above is the main thing you are concerned with there are only three or four things I know that can cause an engine to race like that.I bottom out the large screw
1) The timing is sticking too advanced
2) There is an air leak into the manifold allowing the engine to run fast
3) The fast idle circuit is defective or out of adjustment
4) the idle return spring, cable etc are not allowing the engine to fully fall back to the idle stop, or the idle stop / throttle plate position screw is not adjusted correctly.
Be aware if this car has never run right since you purchased it that sometimes a common hack is to drill the throttle plate to let more air thru at idle on big displacement engines. VW did it on some carbs for other reasons. If the throttle plate is drilled, it may take some sleuthing on your part to figure what carb came on it originally and how the throttle plate was set up. Also make sure that the idle cut off solenoid circuit on the side has not been tampered with or leaking air.