Kudos for knowing your limitations and providing us with model numbers. When you had replaced the fuel filter, had you ran the line behind the filter and catch a sample of the fuel in a clean pan to look for water or debris? If not, do that now. Debris could have gotten to the carburetor. It may be as simple as unscrewing the solenoid below the carburetor and removing the bowl to clean out the bowl area and taking some jet spray carb cleaner and blowing up through the stem of the carb . Are you up for that? Give us a report back.

Check the bolts/nuts on the intake system to make sure they aren't loose.
A vacuum leak in this area can give you the same symptoms and will get progressively worse as they get looser.

These carbs are jetted so lean, that they are already on the verge of surging.
You might want to run a dose of fuel treatment/carb cleaner in the gas. Something like Seafoam or.......
Possibly just a slight build up of gum/varnish etc. on the tiny internal passages could be occurring.