I really think you are not getting all the air out of the brake system, Don't read to much into the ABS brake system for this can be done without a scan tool, and you need to bench bleed the master before installation. This video will help
You need to bleed from the source in this case will be the Master Cylinder, you can bleed the calipers until you wear out the bleeders and you still will not have a good brake pedal. Have a helper and start at the rear line on the master cylinder one pump hold the pedal down than crack the line open let all the air out tighten the nut and let pedal up, Waiting 10 to 15 seconds between pedal pumps, (Do not rush this you will end up with bad results), Bleed the rear line of the master cylinder until you do not see any air bubbles coming from the line nut fitting, Do the same process to the front line of the Master cylinder, ( Keep checking the reservoir fluid level do not run the reservoir dry or you will need to start all over again). This video can help
Starting at the right rear wheel it is farthest away from the master cylinder, Do the same process pump the pedal one time hold down and open the bleeder let the air out and tighten the bleeder and let the pedal up, Wait 10 to 15 seconds between pedal and bleed until all the air is gone at the bleeder, (Take your time wait for the fluid to fill all the reservoirs in the braking system before each pump), Next do the left rear, right front and the left front, Check the braking on the road test for braking power.
(Make sure all brakes are adjusted to specs). Please let us know if this bleeding procedure was helpful and if you need any more information.
Monday, December 30th, 2019 AT 3:41 PM