You may want to check your a/f ratio concentration.
If this has just been noticed with the warmer
weather, it is possible that when you had the a/f changed, it is too concentrated. 50/50 or less, depending on climate, is best. Richer will cause your condition.

If it comes down with the aux. fans, then the radiator, fans, etc are funtioning.
Just an often overlooked check.