Just few weeks ago, my car was idling really rough. So I pulled DTCs and it was misfire on cylinder 1 and 2. So I replaced all spark plugs and two coil packs.

Now today I had the same problem plus no brakes. WTF. I pulled DTCs again today and now it is showing misfire on cylinders 3 and 4.

OK so I need to replace two more coil packs but why no brakes? WTF is up with that?

 

its common for other coilpacks to go after you replace one(s). As for the brakes, check your fluid first. Then it could be a booster or the master cylinder.

 

Well, brakes work perfect when I accelerate and at higher speed. It is only when idling rough, brake pedal feels like when car is turned off. If my car idles ok, then brakes are ok, but not when idling rough. So I would think it has nothing to do with the fluid.

 

ok well thats not even close to what you said in the original post. take care of the misfires and you should be all set.

 

Agreed. You have low vacuum due to misfires, so your pedal will feel weird.

On AWM and up (2001 B5, and all B6), when a coil pack goes dead, save yourself the headache and replace all 4 at the same time if they have not been previously replaced.