A Teenager and His Swinger

I've picked up a set of Monroe shocks that I haven't had the chance to put on just yet. The brake booster froze up while it sat in the barn, so I'm taking it to exchange for a new one. Also I picked up a non A/C heater box and controls for free. Whenever the heater box goes in, major wiring can begin. The car can spin over by the key, but it's losing fire until you let off. Any ideas why?