I was giving a 1999 GTX LTD with a 951 motor. I figured out the bad ground problem. It started up fine ran at idle out of water. I slipped into the water it wouldn't run. I rebuild the pump which had play in it. Slipped it back into the water still having the same problem. Its bogs out in the water. Hard starting. If you pull it out of the water hook up the flush line it runs perfect. Carbs have been rebuild. I am at a lose here. Any suggestion.