Kings3

Im having troubles getting my engine to idle. When i start it i have to keep the throttle wide open or it wont start and if i take my finger off the throttle it stalls. Ihad replaced the glow plug, fuel lines, fuel tank. The only thing is that the part were the tuned pipe connects to the engine came loose one day and i never realized it and i lost the manifold gasket. My dad who is a mechanic made one and put it in there so it has stopped leaking. After i get it running a while once i take my finger off the throttle it dies right away and dont know what is wrong. Me and my dad have spent 3 hours trying to figure out what was wrong and couldnt figure it out. It had been running good before i had lost the manifold gasket but im not sure if that is the problem.