Some quick suggestions on posting graphs.
Use a vertical axis scale of 45dB-105dB every time. This is the accepted scale and allows consistency between graphs for comparisons.
Always start the horizontal axis scale at 15Hz. Extending to less than that makes little sense as you can see the signal is clearly into the noise at that point. The upper horizontal axis should not extend beyond 20KHz. When measuring a subwoofer use 15Hz-200Hz scale.
Use dBFS scale for impulse response graphs. It better shows noise and harmonics.
Use a waterfall scale that matches the subwoofer scale of 45dB-105dB and 15Hz-200Hz (same axis and log graph) for better comparisons against response graphs.
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Yeah, you should have been able to easily get rid of that peak at 36Hz with the EQ of the Ultra. I can't imagine why it didn't work. It's about your only resonance you have, so a single filter in your PEQ should do it.
Your next problem is a dip around 80Hz (crossover area). You should be able to address that with the subs phase and distance timing to remove the dip.
Ignore the 7KHz peak. It is no doubt caused by the cheap Radio Shack meter. That's a standard result when trying to do full range measurements with that meter. Don't attempt measures above 5KHz with an RS meter (and that's stretching it).
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That nice cove you have in the upper left ceiling. I wonder if it would have helped to have it extend all around the theater....
brucek