You have a vacuum leak or a carb. problem. If you have a plastic spacer under the carb you need gaskets on both sides of it. There is a pipe plug or wiper vacuum outlet on the side of the intake manifold. Make sure there is something in the hole. Remove the idle mixture screw & blast air into the hole. Turn the idle mixture screw about 2-3 turns out from bottoming & start the engine. Slowly turn it in till the engine starts to slow down. Then turn it about 1/2 turn out. If none of this works tear down the carb & put a kit in it. These carbs are basic & simple to work on.
