loses power at high rpm's

alright guy's
i have had my b2200 for about 4 months, i got it this way i am just trying to figure out what is wrong. if i hold the clutch in and tac the rpm out it does fine, but when i am in gear i get to like 3.5k rpm and it feels like i just lost all power it spits and studers a little bit. i have to go up hill in 1st gears even on freeway. i get about 3/5's of the gas pedal down then when the rpms get up it quits HELP ME please..... this is killing me

sounds like a fuel issue, not getting enough possibly. or clogged cat.

more info will be needed, is it fuel injected, or carbed (stock or other?)

stock rebuilt engine carb

I had similar problem before, turned out to be a clog in the fuel line. Cleared that right up and that happened again 50 miles later. The ultimate problem was a damaged fuel sock that was letting rust through.