How Do You Remove Thermostat Housing Bolts on a 2000 Buick Century?

I‘m having problems replacing the thermostat on my 2000 Buick Century.  
    I can’t remove the upper bolt on the Thermostat Housing; I don’t know if it’s frozen
in place or, I just can’t reach it well enough to get a good grip on it (or both).  There are
two horizontal pipes in the way, one’s black and the other’s silver.  I tried ‘liquid
wrench’ on the bolt and gave it several good taps, but it won’t budge.  
    To access the bolt better, I tried to remove the Throttle Body.  I removed the nut on
the lower right side of the TB (in front of the small black plate that’s attached to the
black pipe).  However, I can’t seem to remove the stud bolt that comes from the
Throttle Body and extends through the slot in the small black plate.  
    I’m wondering if I should try to remove the black and silver horizontal pipes that are
blocking access to the upper bolt on the Thermostat Housing.  By the way, the lower
bolt on the TH also seems be frozen or, I can’t get enough leverage (or both).  I would
appreciate any advice that anyone can give me.  THANKS!