While driving the RPM's will rev up but my speed does not increase. on 2004 Jeep Grand Cherokee

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It acts like when you have cruse control on and you are going up a slight hill so it automatically pushes the gas to keep you going the correct speed. But only the RPM's increase then go back down. After it does it a few times the check engine light goes on. Then after a couple days the light goes back off.
(2) Answers
Change Transmission fluid - even though it doesn't look or smell bad it can still loose it's pressure resistance. Be sure to change BOTH filters to, but make sure you read the instructions VERY CAREFULLY on the fiber filter - if the "O Ring" is not seated exactly right the transmission will not build pressure to love vehicle - I pulled old o-ring out and use a socket the exact same size as o_ring to seat new o-ring...use only the recommended fluid and a name brand - like Vavoline