I agree with JoeW.
Try moving the clip to the bottom notch on the throttle needle. Take it for a test drive and see how it does. Then try moving the notch to the thrid or next to last from the bottom and repeat test run.
Standard stock setting is 2nd notch from top.
If you've put a bigger filter on your Puch it is sucking too much air in relation to the amount of gas it's getting when you go past half throttle.