Scooter won't go over 35mph *SOMETIMES

[donatello]

I have a 2009 Kymco Agility 125 that has performed well for about a year now. I drive the scooter about 15 miles per day and am able to reach over 65mph typically on an open road. Every few days or so, when I start the engine the acceleration is really slow and I can't go over 35mph. The weird part is when I shut off the engine and start it up again a few hours later, the performance will most of the time go back to normal.
I first removed the cvt cover and replaced the belt since it has been a couple of thousand miles since I last did that - also changed the variator rollers and clutch since they have never been changed. The problem still persisted so I put seafoam in the gas tank to help unclog the fuel lines and carb. I plan to remove the carb tonight and drown it in carb cleaner hoping that will solve the problem. Im hoping I won't have to replace fuel lines or dig into this problem much further. My next guess would be to replace the fuel filter but I am uncertain of what benefits that may provide. Anyone have this problem before or have any wisdom to share on this issue? Thanks!