1998 Chevrolet Lumina - is it the head gasket?

Overheating in stop and go traffic or when pulling small hills. Manifold intakes have been replaced. Water pump too. Radiator flushed. NOT losing water. Can this, nonetheless, be a head gasket problem?

Could be or could be a problem with the fan.

Thanks for your reply. Both fans run when I turn on the A/C. Haven’t been able to pull over and check while it is overheating. I usually turn on the heater full blast and try to find an open road. Henry