Backstory :03 xterra driver/beater with around 206k on it. New plugs, wires etc.

It has an intermittent problem where it has a major hesitation from like 2200 RPM up. More throttle causes more hesitation, but it surges ahead as soon as I let off. This originally had me thinking fuel filter, but when I fuel up, I can usually only add 1/2 gallon or less at a time without it overflowing. Filling up usually takes 15 minutes and is a bitch. I took a look underneath and don't see the filler neck kinked and can't find any plugged or pinched vent lines.

Also related is an intermittent SES light that is usually affected by fueling up, but there is really no rhyme or reason to it. Sometimes it comes one after fueling, sometimes it goes off after fueling. The only noticeable thing is that it usually runs slightly better when the light is on.

Any suggestions or is this a common problem before I start tearing into the thing throwing parts at it? I plan on doing a fuel filter on it this weekend because it's cheap and easy but I don't know where to start with the filling problem.

Start with a trip to the parts store and have them read the code for you.

The computer is telling you it found something wrong, why not ask the computer to tell you what it is. Just about every parts store offers free code readings these days.

Sounds like an evap problem, clogged breather or something like that. On mercedes the breather is built in to the fill tube, they have to be replaced together.

+1 on getting the code read.