This motor is a model T9.9elhx electric start, 4 stroke. I have removed and cleaned the carb, installed a carb kit and a new diaphragm assy(as it was leaking). The motor will now start when I place my hand over the air intake but will not run if I remove my hand, sometimes it back fires through the carb. It absolutely will not run at idle at all. I have checked the starter set(I am told this is an auto choke??) by connecting it to the starting battery and it moves. I am still not convinced this thing is OK since it will only start and run if my hand is held over the air intake. The fuel is new 89 octane with marine stabil and enzymes in it. Put in a new set of NGK CR6HS sparkplugs, still have problem and I'm just baffled with what is the trouble with this motor??? Any help/advice is appreciated(please don't suggest I buy a Johnson although that may be a solution).