Posted for "Matt Hapgood" <matt.hapgood@alumni.duke.edu>:

 Don, I'll provide more information:
 1.  I ran oversquare because I am breaking in the engine (at 180 hours since
 0-timed).  I was told to run high MP.
 2.  I did pull the power back slowly (4" in about 1 minute).
 3.  IO360 A1B6, constant speed, Aerocomposite prop.  Had been running about
 150 degrees ROP.  When I pulled the power back I figure I was about 100 ROP
 (but only for a brief time, as I didn't leave it at the power setting where
 the #4 cylinder wasn't firing).
 4.  Later, while circling the airport, I ran the engine about 100 LOP for
 about 15 minutes, then did the same test.  It still ran rough at that power
 setting, with the #4 cylinder dropping out.
 
 Matt