I've bought a older but never used Picco engine and the problem I'm having is it always shoots straight to full throttle no matter if the carb is fully closed or not. I've done everything, I checked the tank, changed fuel lines, disassembled the carb and one of the O-rings was cut so I changed that, I put permatex on the carb to make a better seal, I checked all the screws and made sure they were tight. All the thing does is it will idle for a few seconds then shoot to full throttle. I'm at my wits end with this thing!!!