Hello my Kia is back in limp mode for the 3rd time

Question

Hello I'm having the same problem again I've replaced the valve body twice already the 2nd time it ran great for about 2 weeks now it's doing again why would it fail again. I will be flushing the lines with Kooler Klean Trans Flush from O'reilys any other Ideas... Ps I got the parts from a junk yard but when I pulled the pan the remaining fluid was blood red just like new on these wrecked Kia's
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