SR Overheats

[DataXUnknown]

Well recently I just finished my SR20 swap into my s13. It drives nice locally, but when I get onto the freeway the temperature slowly starts to rise, eventually just about all the way. Then if I stop and let it idle on the side of the road, it does not go down. It will only go down if I turn off the car and wait it out.

It's wierd because I drive locally just fine, but its like when I hold a constant 60mph or above it will rise. I have a stock radiator, it's a bit banged up but still works with no leaks, I burped the radiator, the only thing that I noticed is that I am leaking a very small amount of coolant. In one of the hoses behind the engine (right near the heater hoses) there is a bit of rust on the actual metal of where its leaking. To fix that I am either gunna get some more hose to cover it, or buy some leak stopper stuff at wal mart.

any other ideas of why it only overheats on the freeway? i have a smic but i cut a hole in my stock bumper just for that.