engine hesitates

[jam3s2k4]

hi, since i fitted my pipercross filter to my 182 cup, in 2nd gear and sometimes third i will be putting my foot on the throttle and i hear a 'whisteling' noise, the most concerning thing is the fact that it feels asif there is no power being deliverd to the engine even though my foot is firmly on the ground of the accelerator pedal, it will do this for a couple seconds sometimes more and then it will suddenly get full power.

any idea's what this could be any ways to fix this without removing the filter and sticking to the standard air box.

thanks!