Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice so we may have to fine tune the answer. Feel free to add any additional info you feel is needed as we go on. Always keep in mind that I am here to help you with any questions.
The 2001 Malibu's I have worked on have had rear drum brakes. With the symptoms you have you either have air in the brake system, or the rear shoes are not tight enough. Tighten the rear shoes as tight as you can get them, and bleed the brakes and see if the pedal is good with the engine running. If it helps back the rear shoes off just enough where they just lightly drag. If you have 4 wheel disc, then the problem has to be air in the system. Sometimes even a bench bled MC can still have air in it. The way you get stubborn air out is to remove the brake lines from the MC and hold your fingers over the holes where the brake lines go. Then pump the brake pedal slowly. Your fingers act like reed valves and wont let air back in, while forcing liquid out. This will purge any air out of the MC. Sometimes an antilock systems will retain air, the best way to get that out is to stomp the brake pedal to the floor, with the bleeder open. The huge rush of pressure will move air out that gentle pumping wont. I would put a piece of hose on the bleeder, and put it in a can. When you push the brake pedal hard, the fluid can spray, and make a mess. Give this a try and see if you can work through this. If you have any more questions, as always, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
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