1997 Ram, pulls to left for second when braking

I have a 1997 Ram 1500 when I apply the brakes the truck pulls to the left for a spit second then goes straight.
Example: doing about 40 MPH take hands off the wheel and slam on the brakes, truck pulls immediately to left, like I did a quick lane change then goes straight.

About a month ago I replaced a section of brake line going to left rear wheel.

Your help is greatly appreciated,
Bruce

I replaced the front calipers and am still having the same problem, any one have any idea whats going on?

Thanks
Bruce

I'd replace both front brake flex hoses, the rubber hoses to the calipers. One is probably weak and expanding a little under pressure. Have seen these cause this issue several times.

Found that the bracket that holds the rubber flex hose was rusted and pinching the hose, pried the bracket open a little bit and that fixed the problem.