2009 Camry 4 cy 5 sp stick 2nd hand car 154K miles.  Acquired this summer.

Recently went to flush coolant system due to age and time of year and found red coolant rather dark.  There may have been some debris in the bottom of my collection container before, but there was certainly some when I finished.  Upon draining and flushing radiator, engine and heater coil, I incurred a heat loss only to find there was an air pocket needing to be chased. 
But now she heats up fairly well but there appears to be a correlation between the heating up consistency and the engine's RPM's.  It appears to fluctuate. My local mechanic said sometimes the fins of the water pump can get worn down and I am guessing that may be the case.  Is it time to replace the water pump?

P.S. How difficult is it to drop engine on this model with just a floor jack?