I saw your post on another thread and you said you had 60mph vibration before. Does the current one feel the same as the old one?
My experience is powertrain or rear hub vubration usually come with noise, so if you do not notice any noise this is going to be a tricky one to judge from internet.
Also, I honestly think for this kind if minor vibration issue, mechanics are usually not good at tracing the root cause. They are too used to more serious issues. So if more than one mechanics clear the suspension, steering and bearing, then I think you either need to look at tires, the other end of the car, or look at powertrain/accessory.
I know you have new tires, but you said the degree of vibration changes sometimes. Do you notice a correlation with ambient temperature? If so, I would say tires are worth looking into. Try changing the tire pressure, and see how the vibration becomes. In my previous experience with tire-related noise/vibration, the vibration felt worse when I lowered tire pressure. The Goodrich tires are known to generate some noise and vibration as they wear.
The powertrain/accessory suggestion also don't match with the fact that vibration persists in coasting. But it will at least make sure the vibration you feel in the steering is clean, and not compounded by multiple of issues. TSX steering wheel communicates tons of info, and I have learned that it can be misleading at times.
04 TSX AT
My build thread - Comfort Sport Build
Phase 1: CT-E I/H, 06 air tube, 06 CAT, reflash
Phase 2: 06 intake cam, 45 VTC, RSP IM, FlashPro
Phase 2.1: HFC, 06 RBB IM
Phase 3: ASP header
Tein CST 8-5 kg/mm with revalve, Progress RSB, Alutec strut bar
Skunk2 Front upper arms
XLR8 BBK (ST-41 4-pot caliper/SS line/One-piece slot rotor)