I appreciate all of the feedback. I finally decided to remove the floor hatch, empty the tank, removed it, filled it will soapy water and let it rinse for about an hour. Drained some of the water out, put more dish soap in and filled it to the top again. Laid out my lines and using a circular saw, cut a 8"x10 hole in the tank around the pick up tubes and sending unit. I drilled out the pick up tubes and templated a new piece of aluminum for the tubes and SU. Had the plate and tubes welded on, disconnected and blew out all of my fuel lines and replaced the filters. Did all of that in three days. Got her back in the water today and she ran like a scalded dog. Couldn't be happier with the decision to take out the tank and cut it open. There was plastic, rubber pieces, shells, rocks, and a ton of leaf/grass debris. I'm assuming that whoever replaced the original tank, got one from a salvage yard and didn't know to clean the debris out of it. Not sure how some of it got in there, otherwise.