One other thing comes to mind.

If you've got too much energy in a particular frequency band, you could look at the dynamics of the instruments in that area. If they've all got a lot of dynamic range, the sum and difference could cause a problem. Flattening the tracks might sort it out without resorting to EQ.

Another quote from my old mentor, Malcolm, who used to flatten all rhythm tracks as a matter of principle -
"When I put a something in the mix, I want it to stay there".

ROG.