When I step on the breaks for any amount of time the idle starts jumping up and down has anyone had this problem? What do I need to do to fix this!
Sounds more like your idle is set too high. When you apply the brakes the ecu thinks your coming to a stop so it kills the injectors to save fuel. The shops guess at the AFM is the reason for my diagnosis... Base idle is 750-800 rpms, 900-1k with AC on... My experience with boosters is a hard pedal feel prior to any idle fluctuation. Good luck!
Had a similar problem, mine was idle screw came loose on tb turned it down and it stopped it. Might want to check screw.
oh, and its OCD, but this is a huge problem..the title of this thread. Your truck has BRAKES. Not BREAKS. You take a break, you use the brakes to stop your truck. Not the other way around.... ok, rant over.
You're right about the idle setting causing the surge too. It's been so long since I dinked with an re I'd forgotten that cause. I've had booster vacuum lines and a vacuum check valve go bad once and the only symptom was rpm surge under braking. It doesn't take much of a leak to cause it.
i had to replace my afm, the electrical chip in it goes out... but you wouldnt be able to keep it running if the afm is out, or at least i wasnt, or anyone else that ive heard of. definitely a vacuum leak and a garage thatll clean up your afm (call it refurbished) and replace youre hose without you being the wiser. or at least thats a what someone as paranoid as me would think...