Quantum 150cc reverse issues

[James]

I'm not sure if I'm posting this in the correct area but recently I acquired a quantum 150cc. When I got it it had plastic on the air scoop thing in between the seats with holes poked in it and taped around it all to hold it on. The guy told me it was because if the engine gets to much or not enough air it won't run right. At the time I discovered that when I covered part of it while driving I could hit the top speed but I was thinking this isn't stock so it should run better without it. I took it off and the performance got even worse. It would bog down or stall out. I unhooked the hose from the air scoop so it was just the hose connected to the air filter box and still the same issues. I eventually tried running it with the hose and the scoop disconnected so it was just a straight opening into the air filter box. Now it runs better then it ever has it has more power and can hit top speed no issues. It seems like to much air or not enough is a issue and having it run without the hose and scoop it runs best. Anyone have any idea what could be wrong with it? Sorry if any off this is confusing or if I called something the wrong thing. I'm not to good with all this but I'm trying to learn thanks