goeddel

Hello all. i have a 2001 mustang v6 and just recently i took it to the shop to have them look at the brakes and along with that they flushed the powersteering out too. Got the car back and now there is a terrible sqeak/squealing noise coming from under the hood. it is alot worse when going at slower speeds. also the car "jumps" like it is going to die and eevryonce in a while like at a stop sign it will die. if you have any ideas on what this may be please help. thought it might be the serpentine belt but just replaced that and it didnt help. thanks in advance.