My Viza Viper gas scooter stops when riding! Help!?

I have a 33cc viza viper gas scooter. I recently got a new gas tank. The Company does not make them anymore so I had to get a different one and had to get my uncle who works at a repair shop to put a wedge or something since it didint fit. When I got the new tank on. It worked GREAT. They put a new racing sprocket in, tuned it up and sprayed something on the chain. I rode my scooter alot after the repair. I probably wasted like 10 miles on gas. Well anyway i started noticing the scooter jerking as if it where stopping, it would still accelerate but at certain times it would make those dying noises.Any scooter owners know when they are out a gas there scooter like jerks and starts slowly dying. well MY scooter started to go that. But its different because my tank was half full. Well it got worse later on, and from this day Every time I start It it dies in 15 seconds or less. I personally think its the fuel lines since they are alot longer and cant reach the carburator. But even if I press the little pump thingy I do it like 20 times so enough gas gets in but its not working I have herd people saying its a air leak but I dont think it is. sorry for the long story. I just want my problem Fixed! HELP!!!! P.S. people PLEASE dont say my scooter is garbage china crap. I just want my scooter fixed okay?