Stalling at low rpm

[Carl]

I have my engine set to idle around 1K rpm. I had turned it up from 850 rpm since the engine would stall as soon as I shifted into gear. I still have a stalling issue, but not quite as bad. My problem is more shifting from fwd to reverse or reverse to fwd especially trying to get the boat back into my slip. The rpms drop to 400-500 and then stalls out. It typically starts right up again, but it gets frustrating and a bit dangerous trying to manuever in and out of a small marina.

My first step is to run off a small portable tank to see if that makes a difference. That will also bypass the racor filter as well. Then I was going to pull a wire off 1 cylinder at a time to see if a cylinder is not firing. I also thought to rebuild / replace the fuel pump

The engine runs strong at anything at or above 1000 rpms.

Am I on the right track, what else should I do?
Thanks

Carl