overheating problems

i have the same problem overheating at a stop light an cooling down when running at a higher speed, i changed water pump,thermostat, an radiator.i still not yet fixed my problem with it overheating. so save you some money check your fan.

IF THIS IS A FORD THE GUAGES READ HIGH AT IDLE. ALONG IT DOES NOT GO IN THE RED. COOLANT ENGINE TEMP SENSOR DIFFERENT FROM GUAGE SENSOR.IT MAY BE OUT OF CALBRATIONS OR INCORRECT.
AGAIN PEOPLE POSTING IS NOT GIVING DETAILS.WE ARE NOT MIND READERS WHAT KIND OF CAR WHAT ENGINE SIZE OF ENGINE MFG.YOU KNOW THE CAR WE DO NOT.CAN NOT SEE THROUGH COMPUTOR TO YOUR DRIVWAY.

may be the fan for the radiator is not working.

NEXT TIME THIS HAPPENDS PULL OVER SIDE OF THE ROAD CHECK IN SEE IF RADITATOR HOSE ARE SUCKED CLOSE. IF NOT THEN TAKE OFF RADITATOR CAP WARM UP ENGINE PUT YOUR HAND OVER CAP HOLE TO SEE IF YOU FEEL PUFFING ON YOUR HAND OR STEAM PUFFING IF SO YOU HAVE A COMPRESSION LEAK FROM A HEAD GASKET TO WATER JACKET. USE A PRESSURE PUMP TO CHECK COOLING SYSTEMS LEAKS,OR DO A CYLINDER COMPRESSION TEST.OR TORQUE DOWN HEAD BOLTS.LEAKING COMPRESSION AT HIGH SPEED IS COMMON IN HIGH PREFORMANCE ENGINES AND DOES NOT SHOW UP AT LOW SPEED ALL THE TIME.WITH NEW RADITATOR DO NOT RECOMMEND USING ADDITIVES OR STOP LEAKS CHEMICALS TO LATE FOR THAT SHOULD HAVE BEEN DONE FIRST.

I had this problem on a 1996 Pontiac Bonneville SSE. It ended up being a bad temp sender/fan sender. The same sender is used for the temp gauge and the fan relay. If I disconnected the harness, the gauge dropped to 0, and the fans came on. The thermostat opens @ 195, the fans switch on around 215.
Use teflon tape as a sealant; don't use gasket sealer. I did this, and it worked for a couple of days, then I got the same symptoms. I tightened the sender another half turn, and ended up replacing the thermostat
for good measure.