My father and I have been trying to get a 1970 Type 1 Volkswagen Beetle running and we had been having problems with it idling. So we took out the carburetor and cleaned all the jets and then reinstalled it. But something else is the matter. After we adjusted the carburetor and got it to idle, we could drive it around for a few minutes and then when we tried to accelerate the car would stall. I know the choke works and the mix of air/gas is correct, and the fuel pump is new... what could be the problem? any ideas?