How do I change the amount of fuel going in to my moped?

I have a Peugeot V-clic and I have been having a lot of problems with it recently. It starts up, not to bad, but then will Rev high and then pretty much shut itself off, it might do this 2 or 3 times until I can leave it to idle, you can't just get on it and go, because again, it shuts down, I have to leave it to warm for about 10 minutes before its even slightly useable. I have recently cleaned the Carb, so it rules that out, I have also changed the fuel filter, and got a performance air filter. So there should be no issues there. Now I need to sort out the fuel/air mix, because somewhere along the line that's been messed with and may be causing some of the problems. I also have a Haynes manual that points toward this, and the automatic choke, although It looks like this could work? not sure, im no expert, It seems my moped has actually got worse since I got my new air filter, I also think I could be getting too much fuel in at one time. Also another question, should I be able to feel air blowing from around the spark plug hole and the bit that covers the pistons (gasket is it?) anyone with any insight or previous experience would be a great help, this is driving me insane!!