302 cooling issue

[BAD BOB]

its a aluminum headed 302 stock water pump (turning the right way) 2.5inch thick aluminum radiator and a electric cooling fan running all the time and i have tried with 160, 185 thermostat, no thermostat and a restrictor plate without a thermostat and it does fine like on the interstate or moving at a decent speed but when i drive then stop with starts running warmer than i would like(200) and wont cool down from there. And it will idle all day and not get warm. I do have a trans cooler mounted to the front and a little torque converter in it. Would that cause enought heat to not alow the radiator not to cool back down? Is it just a POS and i should throw it away or anyone got some ideas????? THANKS