Thermoquad idling issues

I would remove the carb top & verify that the two o rings are in place. Take measurements of the airhorn projection [ the part that contacts the o rings ] & measure the same area [ depth ] in the body. Subtract the measurements to ensure that the o rings are being compressed.

I had a Summit TQ that looked like the airhorn projection had been scraped on concrete! It wasn't even flat, at a slight angle & the o rings didn't seal. This will cause a rich idle/leakage.