Car is jerking as it is trying to shift to the next gear at 55+ miles per hour. it is also sluggish like it is working harder to just drive and the check engine light has come on but aamco transmission and gp auto couldn't find anything work with the engine or transmission. gp auto tells us it is the aps brake system that is locked up thus making the car drive like the parking brakes is on holding the transmission back from shifting. currently has 175,365 miles on a 2003 chrysler 300m