Radiator unless has lots of passages clogged or is covered or coated with a layer of heat insulator material can not cause any overheating. If you have normal coolant flowing on the purge line with engine on then the water pump is working. Check your WP belt tension, clean up the front of the radiator (bugs, leafs and other derbies - that would give you maybe 1% better heat transfer). Water pump 99% of the time when is bad starts leaking.
1) Does it heat up when idling in traffic or driving slowly (city) and cools down once you are moving faster (above 30MPH)?
2) Does it heats up on HWY or up the hill?
3) Does it heat up no matter what in the first 5-10 minutes after start up?
4) What is the temperature?
1. Is normal if it does not go above 228*F. If goes consistently beyond that then check your radiator fans.
2. Is bad, is generally sign of head gasket but could be also loose WP belt, clogged purge line or low coolant level. Head gasket can be detected with an exhaust gas test or if coolant level is dropping but no external leaks, idle is rough and has lot of white vapors out the tailpipes.
3. That is a clear indicator of a stuck thermostat.
4. Temperature variations between 194*F and 226*F are normal.