Leaning for taxi

Earlier this summer I had a problem with a 400 rpm or so mag drop
during runup. Leaning aggressively at 2100 rpm solved the problem, but
it recurred on numerous occasions. I tried leaning aggressively during
all taxi operations, to the point that the engine would barely run,
and that seems to have solved the problem. No unacceptable mag drop
now for the past month. And a lower throttle setting can be used to
achieve the same taxi rpm as in the past, where the leaning procedure
was "pull the mixture out an inch or so from full rich" (my home base,
2V2, is just over 5000 feet elevation). But I still use the same "lean
to peak rpm then enrichen slightly" pre-takeoff procedure as I always
have at this altitude.

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Jim Rosinski
N3825Q