1995 Oldsmobile Cutlass Car vibrates when I use the brakes

I actually have two problems with my car one is that when I use the brakes my car shakes or vibrates and it takes longer than normal to stop I have replaced the tires, brake pads and rotors and it is still doing it. My other problem is sometimes usually when the weather hotter or colder than normal when I start my car the rpm's go way up and then down repeatedly and sometimes makes it stall out. When I start driving after a little while it goes away.