It is possible that the transmission filter is clogged/restricted. The only way to tell is to remove the transmission pan and replace the filter.

If the additive helps, that is somewhat of an indication that the filter isn't clogged badly. If no improvement at all then I'd definitely change the filter.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

I already replaced the transmission filter even put a new gasket. I changed the primary fuel filter but not the seconadry