2002 isuzu trooper transmission problem

I have a 2002 isuzu trooper that has a trans problem. When I would come to a stop then try to accelerate again it has no power . It could be driven like a manual trans and it worked. I took it to a trans shop and he told me I needed a new trans because there was metal shards in the pan, so we had it rebuilt. When he put the new one t and drove it, it is still doing the same thing. He has had our car for a month and still cannot fnd the problem. I really need any feedback I can get. Thanks