I have a 2003 Piper Saratoga II HP with an IO-540. I noticed that while taxiing and idling (usually at around 1200 rpm), I get occasional rpm drops. Every 10 seconds or so, it seems to dip a couple hundred rpm or so for a half second and then comes back. Once I give it some more gas, like during run up or while cruising, it runs smooth. My mechanic checked and said it's normal. My instructor also said it was okay. I would expect it to run smooth at all rpms. Anybody know what might be causing this? Thanks for any help.
