1989 Corvette

I own a 1989 Corvette and i'm having high oil and coolant temp. readings. when i drive the temps. float around 170's for oil and coolant. at a stop light, the temps. rise above 180. but, when i drive the temps stay in the 170's. just yesterday i changed the thermostat and the car seems to be running worse than it was before. the temps. float around 190's. what is average reading for a '89 Vette coolant and oil?

what could be the problem? my next step is to change the water pump.