edelbrock owners please help

[barlow96]

hey after getting my intake polished ive noticed that when riding in sixth gear full throttle my engine starts to hesitat and stumble....its not till i back off the throttle and push it in slowly that it will start to run right....top end is stumbling in sixth gear.....i have the biggest needle that came with the carb ( i think 20E) in it right now....should i order the next biggest needle from edelbrock?? i dont have a airbox and the rest of my mods are listed below..before it would run perfect....now the porcelin on the plug is white with a grayish tint to it...any idea?? thanks

 

[yamarider]

yeah, i'd order a couple of the next sizes up