And the rubber pieces are not under the radiator, they close off the holes on either side of radiator at bottom....one of the rubber(masticated) fillers was missing on mine...added a new in , it changed 5 F........if you have neither, add them in...think they are $14 /set at Ames ,or at least were....tweak the water pump. these are easy/cheap fixes , always go for the cheaper fixes first....I had a three core aluminum (Champion) radiator on mine (did it the last 3 years I had the car)...it brought my temps down the last 10F to 185 in summer...I gradually got mine to go down from 230 to 220 to 205 to 195 , to 185 by doing these different items

also, even though radiator is ok, maybe need to flush the engine?