Thanks for the great replies.
MikeBear, you're absolutely right about 72 being the highest signal. I watched it longer to confirm and it does tend to peak and settle at 72. Previously I ballparked the 60-75 figure after observing the signal levels fluctuate.
WADL seems to be the one with consistently lower levels, fluctuating around 50. I am seeing some pixelation on that station. The other problem stations are WDIV, WTVS, & WXYZ. Even at 72 signal I see the pixelation. Sometimes it goes for a few minutes without any but usually more often though brief.
Rabbit's location on the FMFOOL is accurate, mine came out the same. In the TiVo diagnostics I am seeing uncorrected errors for my problem stations. It also shows 23-29db SNR. Seemed pretty steady at 29 for most. But it sounds like I should try one or both of those filters. I don't suppose there's any local stores that sell those.
I think before I do that I'll play around with my antenna location more. I'll get a longer cable and try putting it up into the attic and also outside to see if I can get a spot with less reflection issues. I have vinyl siding and asphalt roof. I don't think there is any aluminum; just drywall, insulation, and wood.
Rabbit, you mention the Antennas Direct C2V. I wonder if I would have better luck with that antenna. When I purchased HD Frequency Cable Cutter I came down to basically deciding between those two.
The Wirecutter review pushed my choice to the HD Frequency Cable Cutter.
I'll find the cable amp tonight and post what model it is. It sounds like it shouldn't be used though. My understanding was it was needed to feed cable TV to an 8 line split in my previous previous house. This setup with the TiVo doesn't require me to use any splitters. However the TiVo does have 4 tuners so the signal must be split amongst them somehow.