700r4 Overheating

[AusTx68]

So when I installed this tranny I did not have the tv cable properly set. I didn't realize this until 100 miles later. I then went back and corrected it. Since then it has been running fine (maybe 75 miles). Then all of a sudden it starting overheating. At first I thought it was my motor. Later I realized the fluid temp was so high that it was overheating the water in my radiator. I was on the road when it happened. If I threw it into neutral and brought up the rpms it would cool down. When I hit the road again it would heat up in less than 5 miles. If I sit and idle the temp stayed normal. I'm confused as to why this started happening when it was running fine after I set it. I guess it could have been overheating but only now is getting high enough for me to realize it.