Weird overheating issue KA24DE

[jdm_s14_zenki]

So i just picked up this S13. Runs good and fine and everything, but today when i was driving, seems when i give it alot of gas, my temp gauge goes up. and wants to overheat. not sure whats going on but so far ive done:

checked water. good
no leaks.
thermastat SEEMS to be working, both hoses are hot.
I have a koyo alum. radiator with clutch fan, no fan shroud though.

I can drive all day long without it overheating, its just when i floor it, it gets hot. then if i stop flooring it, it goes back to normal.

I did cut the top radiator hose to shorten it because it was too long...some water spilled out, but i replaced the water...i dont think thats the problem..

any ideas would be cool. thanks.