I changed primary and secondary filters about 20 hours (engine clock) ago. Last week while motoring my 3HM35F @ 2000rpm from Nantucket to Martha's Vineyard the engine suddenly decelerated, shuttered, blew out a huge puff of white smoke, banged (I think backfired) and then started to run smooth again. I decellerated immediately to about 1000 rpm. This all happened in about 30 seconds. I recalled two weeks earlier that a neighbor at our marina sufferred the same symptoms (but no backfire) and was told that he had an air pocket in his fuel system. While still underway, I bled the system at the secondary filter, fuel compression block and each of the three cylinders and it seemed that I did get some air out at the filter and compression block. I've now run another 10 hours with no problem. At the time the fuel tank was nearly full and sea conditions were calm. My question: Is this symptoms of an air lock? Did I do the correct thing? Do you have any suggestions? Thanks in advance.