1973 Plymouth Scamp accelerating/braking issues, please help

Tune-up parts and technique suggestions in this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. "Remanufactured" carburetors are junk. Buy a good-quality rebuild kit; I like the ones from www.daytonaparts.com best; they have a better inlet needle/seat design less prone to flooding than others. Install a new float, Walker #100-14; the float is nitrophyll (foam) and over the years they absorb fuel and no longer work right. Make sure to use the correct thick (11/32" or so) insulating carb base gasket.

Find the one and only hose that connects to the distributor and make sure the other end of it goes directly to the carburetor without stopping at the widget on the passenger side of the firewall (if your firewall widget, a primitive emission control device known as an OSAC valve, is still hooked up -- follow its other hose to the carburetor, then bypass it by connecting directly from carb to dist).

Make sure your manifold heat control valve is free, not stuck, and is operating correctly. You may want to do the Fuel line mod.

Try a base ignition timing setting of 5° BTDC (with engine idling at 750 rpm, hose disconnected from distributor and plugged).

Keep on top of the valve adjustment.

Also you will want to get the three books described in this thread as soon as you can.