half throttle stumble help!??

[jasonsnova]

sorry guys i also should of mentioned its a 4150 hp 750 cfm. also a little light bulb just popped in my head.... a raceing friend set the carb up for me when it had the auto/highstall conv and bigger cam....he took the powervalve out and blocked it off. could that be my problem?? im thinking that it didnt do it before because it was basicly a drag race set up , but now it is making alot more low end and maybe it needs the powervalve??? i honestly dont know alot on how they work.....