I have a 55 with a 265 and powerglide. It runs fine at idle but will not accelerate at all. Wide open downhill it will run 42 mph. It acts like the timing will not advance properly. It will not crank when it is hot either. It sat for almost 3 yrs beforeIi got it. It has new plugs, clean tank, fuel filter before and after pump. Cleaned the carb and also put on another carb (rebuilt but not by me). Runs about the same with both carbs. What could cause this? Still has points in dist.