Hey guys. I need some help. I have a 77 slickcraft ss 235 with a omc 190 hp. I just did a motor swap due to a cracked block. My issue is that when I run the engine in my driveway it runs great. No sputtering or hesitation. But today I took it out for the first time and had some issues. First I noticed the whole boat would shutter at around 700-900 rpms. And then every time I would try to go over 1000 rpms it would die. I could get it to go over 1000 rpms if I gunned it. But it would still have that hesitation at 1000. Amd then when I hit 3000 it would start to fluctuate the rpms. So it did this right away on the water. But if I took it out of gear and just ran the throttle it would run just fine again. So I know it has to do with having a load on the engine. Any ideas on what I should check or do. I'm at a loss here and could really use some help. Thanks.