I've recently noticed a loss of power, most noticeable in climb and cruise. It seems I've lost 7 - 10 mph in cruise. I had the prop overhauled last year, and I'm just coming out of annual now with strong compressions, no loss of oil. 1975 M20F, ~4,200 hrs on airframe, mid time engine. Anyone else experience the same thing, and most importantly, what was cause and correction?