92 storm coolant issues

After removing my catalytic converter, my car began running hot, but only once a week, i crossa mountain every day to go to work, but my car only runs hot one day of those 7.
I have changed the thermostat and radiator cap and have two fans wired up to my radiator that run constantly.
there is no milky or frothy oil mixture on my dipstick, I haven't lost any power in my car, uphill or on the highway, I haven't expierenced any coolant loss, but the reservior tends to get full and i have noticed a lot of white bubbly substance in the overflow reservoir lately.....untill this i had almost ruled out a head gasket, and have been leaning towards a clogged radiator. My questions are this:

is there something I have missed after all these tests?
could it possible be a BHG and not know it yet?
What Is wrong with my car??? :)

Thanks for any help..