[MOTORHEAD]

Sounds exactly like my car used to be! 2 problems ; 1. not enough airflow thru radiator,
2. in traffic or stopped, engine is idling, so waterpump is rotating slowley, not moving enough water fast enough. This is where an electric waterpump would be handy, or there are inline electric pumps that you just install in the bottom radiator hose, but either way, you're looking at $500 +, and you still need to move the air thru the radiator. We both live in hot areas of the country, which doesn't help.
A few other members of this site have threads on installing a certain two speed fan/shroud used on some Ford products, with great success, so thats what I did, and it solved my o'heating problem. I also have a thread here on the subject, do a search for "Taurus fan ". I don't remember the details, but most info is in those posts. Fans are available new on amazon and other sites, and are not expensive!

Ted