A rebuild kit will not fix this. Your carburetor's throttle body is worn and needs to be rebushed. There's no prefab bushing, and this is a precision machining operation—not just a simple matter of removing a worn-out bushing and installing a new one. From the factory, the steel throttle shaft bears directly on the aluminum throttle body itself. With use and age, the hole in the throttle body gets wallered-out (a Texas term meaning "wallowed out") and air leaks in at the throttle shaft/body junction. The repair operation consists of carefully marking the placement and orientation of the throttle plates relative to the shaft and body, removing them, removing the shaft, overboring the throttle body, and installing bronze, brass or Delrin bushings to restore a tight fit that still permits free movement of the throttle shaft. The throttle plates and the throttle bores have to be carefully marked before disassembly so the plates are put back in exactly the same position, otherwise idle and low-speed operation of the carb will be screwed up.
It's been years since I had one of these done. I used to patronise G&S Auto and Machine, who advertised the service in Hemmings and happened to be local to me. They charged about $35 to $45 depending on the type of carburetor, and offered fast turnaround. 303-795-1412; they may still be rebushing throttle bodies. his is a service you have done at a competent machine shop, and then you go through the carb with a rebuild kit. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. You can't get a new carb from RockAuto or any other parts store, just "remanufactured" junk. Don't waste your money (and the "remanufacturers" don't rebush the throttle shafts).
