16" champion electric fan and shroud, any good?

And just how hot is it getting? I didn't see that in your post...

I have a 26" Champion 3-core with dual Ford Contour electric fans in my 451 Dart and it will idle at 182F all day long in the summer. At sustained 65+ mph (3300 rpm) on a 93F day, it slowly (over 15-20 min) crept up to 198. Once off the highway it gradually returned to mid 180's.

If you have a clutch fan, make sure the clutch isn't worn out and loose. Also the fan should only be part way into the shroud. (When the fan is all the way inside, the airflow is actually worse).