I am trying to revive this dishwasher, it is a GSD4930Z00WW. When I got it I tested it outside and it had no problems draining(I ran 2 loads in it). I now have it inside and plumbed into the sink drain(no disposal). It will drain throughout the cycle but will leave it with standing water in the tub afterwards. It takes about 3-4 times of reseting it to get it to drain.

What I have done,
Cleaned both screens
Checked out the piston(was chewed up, replaced it)
Hooked shop vac up to drain hose and reset dishwasher
Drained dishwasher into bucket. It looks like a healthy stream coming out.
I verified that the main pump is spining.
The drain valve moves good, not too loose not too tight.
The drain pump runs(it runs right at the end of the drain, I am guessing that is how it is supposed to work)
Checked flapper on drain pump, okay.
Removed drain pump housing and checked that impeller is connected and in good shape(it is)

What does the body valve actually do? Could that cause it?