Issue with brake pedal? at 20 mph or lower-2017 tundra crewmax 4x4 HELP

Help! Going back to Toyota a third time. Here is the story: 2017 tundra 120,000 miles on her. Went on a trip to KY from FLorida. When I brake, its fine until about 20 mph or below.The pedal pressure goes down and acts like ABS kicks in but no light. Sometimes I get a hard downshift. I put all new brakes and rotors on. (Aftermarket). The problem kept happening. No codes, no lights. I replaced the needlepoint bearing to the bushing from east coast gear supply. I replace the cv axle due to it having a lot of play in it after removing it. (Aftermarket CV axle). Still have the issue. I finally go to Toyota. (Scared because if no codes the newer techs don't know how to mechanic). They turned the aftermarket rotors stating they weren't flat. Took it 5 miles, same problem. I decided to replace all brakes and rotors with Toyota. Went up to NC this past holiday and within 400 miles, same poblem. Going to Toyota again this weekend- very ticked off. I'm hearing a low growl in the middle of all this. They are stating that that is the tire noise. BF Goodrich AT. It's not the tires. I've had them on for 1.5 years. Great tires by the way. I'm at a loss and am wondering if it is the front differential. Any help or guidance is appreciated. I have NO faith in the Toyota techs. No code on a computer they don't know what to do. HELP! UPDATE BELOW:

 

Perhaps try bleeding the brakes if you haven't already.

 

After 5 months of dealing with no light on the dash and no code showing the problem of braking and a pulsing in the break pedal (when breaking). A code finally shows. The whold dashboard is lit up with the code below. After researching what it could be, I concluded its the left wheel bearing. Taking it to Toyota, they said its the Left Wheel Sensor. I said no, left wheel bearing. Of course they showed me the codes. I agreed and stated if I have to bring it back, they need to take off the monies spent on the wheel sensor. Well, after two days the code is back. Take it back to Toyota and yep the let rear wheel bearing. Money for the sensor was taken off the replacement of the left wheel bearing. I researched the heck out of this and hope it helps someone else. If you get this code, check the wheel bearing on the side the code comes up with for the wheel sensor. Toyota really disappointed me in this but I'm glad its over with until the right wheel bearing goes.