This is the stock carb from my mercruiser 3.7. I think it's similar to the v6 carb. New kit installed after a 4 day dip soak, it's clean.ran a wire, and carb clean spray, and compressed air through every passage. It starts, idles, runs, and REVS great. Right off idle theirs a puff smoke and a hesitation, if u open throttle slow. If slam open, it seems ok. I've set float 4 different heights, no change. I went from 66 to 58 mains, REVS better on top, but no change in puff smoke. I found a parts carb on shelf and changed power valve, this cut the puff smoke down,but still their. I tried fuel pressure from 2.5 to 4, no change. The longer it idles, the worse it smoke puff. Looking into carb while running, no fuel dripping. Pump squirt seems normal. Any ideas?