Modern Vespa

My top speed is about 10% less in the AM when its 60-65 F vs when i get off work at 4:30 PM when its 80-85F out and scooter runs at full speed. i've checked the air filter which is only about 1.5 yrs old with maybe 2.5 k miles on it and it seems clean, i adjusted the fuel air and idle screws where i think it should be. Have kept up on all basic maintenance, oil changes, tires, battery, spark plugs, gear oil etc even adjusted valves once, scooter has 7,150 miles on it. i dont remember having this issue last riding season, One other note is it starts right up in the AM with no gas, but is much trickier to start up in the afternoon, need to finesse the gas for a few seconds so it doesn't die, I'm guessing it has something to do with fuel/air but can't sort out how all the pieces fit. any ideas?

Maybe put some coffee in the gas tank?

On a more helpful note - is the choke slow in opening? Any black smoke out the exhaust? I'm assuming you have a carb.

yes i have a carb and it has been cleaned out multiple times, i also run chem tool through it periodically, i haven't noticed any black smoke out the exhaust, i do wonder about the autochoke though, it seems to have been more responsive in the past i.e. the rpm drops/increases were more pronounced and noticeable, it still does ramp up rpms in the morning then drop them after a minute or two, but it feels like its more sluggish and sloppy perhaps. I did feel the autochoke and it did get physically warm to the touch on startup so it does appear to be working in some capacity, the plastic/rubber cover on top of the autochoke is partly melted in the middle like it got too hot at one point, don't know if that has anything to do with anything but just thought i'd throw it in there.

Maybe wake up later. Works for me.

The magic juice you are running through the tank isn't helping the bike run any better. If you switch to a good top tier gas from a busy station, you will be giving your engine what the people who made it intended it to run on.
And yes, replace the melted part. When a part melts, it seldom improves it's functionality.
There is no good reason to clean the carb over and over again. You reach a point where you are more likely to break something than to make it run better.