ABS Brakes/Speedometer not working properly

1) Inherited this truck from Grandpa, it needed a little work.

2) Wanted speedometer to work.

3) Found both ABS sensors unhooked, and reconnected them. Everything seemed to work fine.

4) I noticed a few days later that the brake pedal would pulsate (forced back on my foot) while applying the brakes it would happen at about 10 MHP. My speedometer seemed to work fine.

5) My dad replaced the master cylinder; it did not help.

6) We then had the Toyota Dealer service center look at/ and make a diagnosis. (No repairs by them)

7) Their diagnosis was to replace both rear ABS sensors. So, I unbolted and replaced both. I test drove my truck and noticed that my speedometer was not working at all.

8) Just to see if I could make things better, I pulled into a parking lot and snugged the bolts to both ABS speed sensors, they may have turned about one turn each.

9) I was traveling at about 40 MHP and looked over and noticed the speedometer was registering about 40 MHP (seemed about correct).

10) I'm not a mechanic and this is my first vehicle, I'm paying more attention to the road and not the speedometer. I do not recall exactly what the speedometer is or had been doing for the next day (I thought it was okay), But I quickly noticed it was not registering at all until I was moving about 20 MHP, then from 20 on up it seemed to work like it should.

11) The next day (without trying any kind of fix) It was not registering at all. This is where it stands now.

Can you help me fix it correctly? That is make the speedometer work and have no ABS related pedal or braking issues #2 and #4)?

I have relatives who are more experienced with vehicle repair, who can assist me.