I've been on vacation and have not attempted any of the suggestions, but just had to say thanks to all; quite impressed by the responses and timeliness.

I will post back with a solution (hopefully).

Carb/linkage fixes have been covered. Another possibility--sticking shaft or weights for the distributor advance. good luck--Dave

Let us know which one of the fixed proposed (if any) helps.
That is what makes this forum work!
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George Downs Bartlesville, Oklahoma

I had the very same problem and it was a small vacuum leak. Check if there's a small spigot underneath the rear carb at its base that is used to feed the vacuum advance/retard governor. If no governor, this spigot should be capped. Perhaps the cap has fallen off.

Cheers,
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Barry '67 122S "Betty" (Rest in parts), '69 122S "Veronica"

Each throttle butterfly is held in its shaft by two screws. If any of those screws loosens, the butterfly can shift slightly and hang up on the carb barrel when closing. Check for that, just on the off chance.

As suggested, make sure your linkages are well lubed and the throttle plates are working properly.

After that, I'd suspect a vacuum leak, timing problem, incorrect PCV orifice or brake booster leak.

There really are few possibilities. It should be easy to nail down quickly.

If both the throttle return springs at the carbs are in order, if the linkage moves freely from pedal to carbs, try adding some tension to the pedal return spring ( L side of passenger footwell) by turning the screw there.
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Patrick, '68 220 (used to drive 240s)

Jeff;

It may be as simple as a sticky linkage...I'd start with a drop of Triflow or synth oil on all pivot and control points of throttle...being a mechanical carb, the throttle plates need to return perfectly to their stop...if they stay hung up in the slightest, that's all it would take to raise your idle...don't use WD40 unless you would like to repeat the procedure next week, and every week after that...useless stuff as a long-term lube...it's mostly solvent...

Cheers