[jclark003]

Hard to,say what the PO put in the tanks. Alcohol based additives or a fill of E10 left in the tank during winter layup could account for what you are dealing with. Good info to share for sure.

Still would consider getting the tanks cleaned. Filters have a habit of plugging up at exactly the wrong time. Loosing an engine while coming in your inlet during 5-7's would probably not be much fun.