If you hear noise from the carb, puffing like you said, its most likely valve adjustment again. Having never worked on a 235, but plenty of other engines, it sounds like the adjusting nuts are not staying tight or the studs in the head are pulling out. A jumping needle on the vacuum gauge means something is wrong with the valves. Don't bother with the new carb till you get this figured out, you don't want to add a problem on top of one already.
Joe
