As above, how olds the fuel? Also checked basics like fuel filter, lines, ignition components? Changed the plugs?
Stuffs not like it used to be back in the day, ignition components fail, fuel filters can get blocked / reduced flow.
My high spec 1380 wouldnt pull clean past 90 last year after winter recomissioning, combination of poor fuel filter, slightly iffy rotor arm & cap and a couple of spark plugs not fully right.
Good tank of V power & italian tune doesn't harm.
Had this on my 998 last year, we changed distributors, coils etc as it wouldn't run to get the emissions tested... A fresh tank of Tesco 99 octane fuel then let it run until the old stuff is used up.
So my advice now is to drain the fuel from the tank, lines and carb, refilling with fresh stuff, clean the plugs and try it