2005 SR5 Tundra Strange Shifting and Loss of Power

Hey everyone. When driving the tundra around the check engine light came on but ran and drove fine. Recently we noticed that the 1st to 2nd shifts fine and if you try to acellarate the engine revs but stays in 2nd until you let off a little, then it shifts. On the highway if you floor it, it down shifts and doesnt do much. Usually the truck down shifts twice then screams on the highway like it should but doesnt. Its defiantly not the tranny. We had this issue before but was because of a leaky exhaust. The exhaust is leaky again but this time I have codes.

Thanks!