The engine cooling fan is likely slipping. With a warm engine, switch off the ignition while watching the fan blades..... if they don't stop immediately with the engine, the fan clutch should be replaced.

And don't replace the radiator - if you think it's clogged, have it rodded out by a radiator shop. The Mitsu radiators are high quality and worth rodding, as most aftermarket replacement are not as good.

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum