The picco 26 is a good engine, but can be a bear to tune. Does yours have the mid speed needle? If it does, did you mess with it? Never touch the mid speed needle.

Anyway, it's hard to tell without being able to hear the engine run. If you had it tuned and it just started doing this, it may just be a temp change that's doing it. It is getting warmer and may be running fat on the top and bottom.

I like to run my engines a bit fat on the bottom. I tune my engines so that they will only idle for 5 seconds or so before they start to load up. If I let one of mine idle for 30 seconds, it would probably kill when I got on the gas.

Without being able to hear/see the engine run, the only adivse that I can give is to go back to the stock needle settings and tune from there. I don't want to be presumptuous, but when you tune, leave the bottom needle alone until you have the top tuned. The bottom really only affects right when you get off of the line anyway (unless it's super fat). When you tune the top, don't just run it up and down the street and start turning the top end screw. Run it for a few minutes and listen to it. Get it to where it's running the best, then back off on the screw about 1/16 to 1/8 of a turn, to take it a bit easier on the engine. Better yet, don't push the engine. Just tune it to a satisfactory level of performance. As long as it doesn't sound like it's choking on fuel or gasping for fuel, and you see a thin trail of smoke, you are good. Once you have the top set, tune the bottom. If the engine seems like it's just running too good, you're probably too lean. LOL