Brian, This has happened to me on several occasions. It does tend to get your attention.
In my case I believe it is related to over-leaning. If I lean to right to peak EGT at high cruise I can expect a "hiccup" within a few minutes. If I lean to peak then go 75 degrees or so rich "It" does not happen. I will not speculate on the mechanics of this phenomenon here. My carb is also a POSA type (Aero Carb) on a Revmaster 2100D. I do not use a filter other than the gascolator. Cheers Owen www3.sympatico.ca/omacphe "I was out flying for the first time in 2 months (due to job and WX). When during a fast low aproach at full throttle the engine skipped a beat."
