hi had the same problem with my apc 40 which caused the demise of my trainer cut in mid flight and the instructor crashed into the trees i knew nothing about tuning engines found an article on the web, you need to get your mixture screw set up this is the opposite side to the throttle arm this should be set at full throttle , wind it out just till the engine starts to burbel then gradually screw it back in till the revs pick up nip the fuel supply pipe to the carb if it revs up mixture is to rich (wind mixture screw in) if the engine dies mixture is to weak(screw out) if revs pick up for a few seconds then engine dies the mixture screw is set right, to set the idle screw open the throttle from idle if it splutters its way up to fullrevs then idle screw is to rich,(screw in) if engine cuts when reved up idle screw is to weak(screw out) when you have it set up right put engine to full revs pick up the plane and hold it up at an angle this is the lean out check if the engine cuts you need to give the mixture a couple of clicks out, one of my club mates also told me when you get the engine set right give two or three more clicks out on the mixture screw as the engine will lean out when the plane gets in the air hope this is help ,also watch your fingers as i learnt by bitter experience