sr with koyo overheating on freeway??? wtf??? help please!!!

[uthemofo]

Ok so i just put in a koyo that i got used with some dule flex-a-lite fans, yes i now know that they are crap but i got the fans and the koyo for $200 so no complaints. So after one track day i decided to take those fans out and get my self a tarus fan, I installed the fan and actually made my self a piece of aluminum that covers the whole rad. this fan works way way better. i have it wired to a auto temp sensor that come on between 180 and 220 and i can adjust it, i have it set at 170 and it runs cool all day long. UNTILL i got on the freeway, i was cruzin on the freeway at like 65 or 70 and then it started to climb in temp... im like wtf why would it do that especially since its a nice cool night on the freeway.

it did this all the way home, i would stop let it cool then it would heat back up again, stop cool and same thing.

my question is WHY why would it do this? maby the rad is partly clogged??? maby my thermostat is being wack? stock one by the way


i honestly dont know

please help me

thanks
matt