Brakes/Rotors Pulsating

Hi everyone,
I bought a 2016 V6 PreRunner with 70k on it in fall of 2020. It's been great except for the brakes. Every year or so they start to pulse when braking at high speeds. The steering wheel shakes back and forth pretty severely after a while, and you can feel the uneven friction on the pads when coming to a stop. The fix has always been to grind down or replace the rotors. Which works for a while. Then the issue returns.
I brought it to my local mechanic, whom I trust completely (he now waives the labor cost when replacing the rotors), and he's stumped. So before I turn in my Tacoma for a new truck, I thought I'd check and see if anyone else has the same issue and if they've discovered a solution. I'm just not willing to spend $400-$500 on new rotors every 10-12,000 miles. Something is causing it and I can't diagnose the "upstream" cause.
Any help would be greatly appreciated.

 

How are your calipers? Are the brake pads wearing evenly?

 

Did they actually check the old rotors (clamped in place) with a dial indicator? The Toyota brake pads and rotors don't "self clean" very well and I've found that to be a problem. Just tearing the whole thing down for a thorough bath - cured the pulsation on mine. Same parts went right back on and didn't pulse. Rotors weren't warped at all - calipers full of baked pad dust.

 

Welcome to TW!

 

He told me the brake pads were fine. I'll ask about the calipers, but I assume he examined them. Again, he's good and I trust him.

 

I found mine by securely clamping the rotors with properly torqued lug nuts and mounting a dial indicator. Pads and calipers weren't the first place I looked due to past experience with Fords.