[cdowns]

first off what are you using to get those temp readings?? if its a dashboard gauge that could be your percieved problem//a good accurate thermometer is a good shop tool to have
how old is the radiator and has it ever been boiled out and pressure tested by a radiator shop?? a clean well flowing radiator cools alot better than one with many years of accumulated deposits//the over the counter cooling system flushers is money flushed down the drain IMO