[Gaz64]

If the plugs have done 100 miles already, they would show up an average of all conditions.

Lot's of idling would make the check almost null and void though.

Could be worth removal of all for inspection.

But as Brent has said, it sounds like a slightly late PV opening.

No carburetor will be exactly correct, most can be 90% straight up, and then some further tuning is necessary.