1985 tri-z 250 Fuel Pump problem

[southtexas250r]

i just baught a 1985 tri-z 250... this guy told me it an but would starve itself out of fuel... i got it running sand yes after you get up to speed with it and start pourign the throttle to it it will bog out but wont die out will still idle.. i check the fuel pump no holes in diaphram checked vacum line checked fuel lines checked carb all looks good and works but pissed cause it halls ass for the first two gears but is doen after that. can somone give me some ideas about what it might be wrong????????

thank you in advance