71Demon540 said

It sounds governor related. I would check the governor pressure and the return line pressure before pulling the valve body. I’d also get a pressure check on the kickdown/front servo. That will help you eliminate if the servo is even trying to apply or not. Did you do any air checks before final assembly?

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Yellow Duster said

Update time. I pulled the valvebody back out and rechecked everything inside. Nothing jumped out at me. Somewhere in all my reserch, I remember reading that a stuck accumulator could cause this. Went to pull it out and it didn't want to budge. Had to get a pair of channel locks after it. It is a brand new Sonnax unit. I have a good working trans out of my Duster sitting on the floor, so I pulled the valvebody (B&M shift kit) and accumulator out and put them in the truck. Now shifts just like it should. Don't know if the valvebody or accumulator fixed it, but at this point, I'm happy.

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