Since it happened after getting fuel at a different location, I would drain some fuel into a jar and check for debris and water before going nuts with the mechanic. You can also get lots of water and debris in your fuel it the tanker is filling the tanks when you are filling yours.
I would also inspect the spark plug Wires, my Black Max idles like [censored] sometimes, when the gas is bad or old, or when a spark plug wire is not seated all the way. You can test the Wires by putting an old AM translated radio near the plug Wires. Way old school.
I run seafoam at one can per 14 gallons all season long to condition fuel and reduce carbon build up....good stuff.
95 Skeeter 150ZX w/ Merc XR6 150
Ocean Kayak Prowler 13
59 Yellow Jacket w/ Merc 50