Thanks Dan. Will try this - never had courage to do it before ("big pull"). My original question still stands. That is, since I spent a lot of time leaning very slowly in the Redbox area, why did my engines do so well?
You aren't going to hurt anything by pulling the mixture too far, even if you do it quickly. You know you are lean of peak when you feel the power decrease. If you accidentally pull it too far aft, you'll either feel rough running, or it will get very quiet, depending on how well matched your fuel flows are. In either case, ease the mixture forward until the engine is running smoothly. Then, after a pause to let the EGT indications stabilize, start easing the mixture forward looking for peak EGT.