Hi. I have a 1970 Mach 1 Mustang and I'm having some trouble with it. When I go to start it up it won't stay running. The battery is fine and all the fluids are okay. I have to put it in neutral and keep my foot on the gas a little to prevent it from dying and once my foot comes off it dies. Could it be the carburetor? I but a new carburetor in a few years ago but I guess it's possible that I need a new one again. I have a 351w engine and have done no mods to it. Thank you to those who reply!