Whirlpool Dishwasher won't drain properly

[mikelewis721]

My Whirlpool Dishwasher will not completely drain. I have to push the cancel button several times at the end of the cycle to get all the water out. It is draining into a disposal and I can see a trickle of water coming out when draining. I pulled the dishwasher, removed the bottom arm and all covers to see the chopper and rubber check valve (flapper). No obstructions. I removed the drain pump and no obstructions. I blew thru the drain hose and the water blew out into the disposal and there appeard to be no obstructions. I figured there must be a problem with the pump. Replaced the drain pump and experiencing the same problem. Any ideas? Getting ready to replace the dishwasher.