First the valve is in the wall and you removed the valve stems.
My guess is that when you remove the stem the water flows through the valve and out the valve stem holes with no restriction because the problem is something stuck in the valve where the water mixes or shower head.
Did you remove both hot, cold and diverter stems? Is the tub spout the diverter? Is it both hot and cold that won't flow?
Please use smaller type when responding large is harder to read.