I have been fighting with air in the fuel line and have rebuilt warboro carb , changed primer bulb. wraped wire around clamps on primer bulb, changed fuel filter on the line from the tank to the primer bulb , changed fuel line from fuel tank to to the filter below the primer bulb and still did'nt work. The air in the fuel line was visibly building just before the carb and under full throttle would stall the engine until you dropped the rpm. The Problem after all this was a plugged fuel line filter in the gas tank. The carb was sucking air from anywhere there was a connection even though there was no visible leak anywhere. The polini filter is made of a changeable cotton fuzzy type material that I cant find . There was a gummy residue in the tank that plugged it. My own fault maybe as I have been leaving some mixed av gas in the tank and it sits for 6 months while I am not able to fly. Replaced the tank filter and it runs and idles perfectly