When I lifted the rear of my truck I had a similar issue when decelerating or braking, I found that not only had my caster changed but my toe was also pitched in a little too much by almost 1/8 of an inch from what I generally set it at. So since I was going to lift the front I went ahead and did that, well that fixed my toe but the caster was still out so I shimmed the front and it went away.
