It was that tank of bad gas. Suck out some from the bottom and let settle in a clear jar. Mine did that and actually the only problem I have ever had. It also lost the idle which was what was most noticeable. . Took me two weeks figuring it out. Few new loads of ethanol gas fixed it by absorbing the moisture.

9 times out of 10, with a fuel filter, you loose idle and power way up there in rpm.