I have a 2006 Cobalt LT and it has 139,000 miles on it. Under braking from highway speeds the car will sometimes have a slight shake and I'm wondering if it just needs new pads?
When you stop and get a pulsating pedal it is usually the rotors are out of round and need to be cut.
This is usually done with a normal brake job. If you don't need a brake job at the moment (pads still in good shape) you can wait to get the job done if you can tolerate the pulsation.
If the pads are fairly new then you can just take the car to a local professional mechanic and just have the rotors cut and the old pads reinstalled. This is usually not the normal practice but there are no safety issues with procedure.
A brake job is usually the normal fix and it is worth the price of the brake job knowing it is completely done the right way and you won't have to worry about it till the next brake service.