I recently bought a 57 D100 with a 318 in it. I get it home and start having issues with it back firing through the carb, not running smooth under a load like driving up a hill and the HEI distributor failed. I switched back to a points set up, changed the timing chain, new plugs, cap and rotor. It runs better and the backfiring has stopped but i still can't get it t idle at a lower prm or go in gear without stalling. We had a timing light on it when we finally got it running again at it was 30 before top dead center at about 1700 rpm. Adjusting the idle lower and it will idle rough and stall or stall as soon as it is put in gear. Also, the idle will raise and lower a little on its own so we think there is a vacuum issue but we have checked all carb seals and around the intake with carb cleaner and couldn't find a leak. The only other thing we can think of is that there might be a valve issue that is causing the problem. Any advice you guys have would be appreciated.