Periodic ( once every few hours), but now more frequently (at least once during the past 3-4 flights), the right engine (IO520) loses power. This has been going on for 2 months. It can be from a barely perceptible fraction of a second to half a second where there is a noticeable yaw. My mechanic insists there is water trapped in a crease in a bladder. That made sense the first couple of times but this has persisted. It usually happens so fast I don't see the JPI engine monitor. But, one time I did see all the CHT's drop off for that short period (less than 1 second). ?