Mike,
Don't spend big dollars on new gear like rotor's and calipers until you fix the problem you have with the car now, otherwise there is a chance you will still have the same problem afterwards.
Replace all the brake fluid with fresh clean stuff and bleed the system. Look at the pads of all four corners and replace any that are worn down to the backing plate. Inspect the rotors for thickness and any cracks. Check your calipers push out the pads smoothly.
Tells us what its like to drive/stop after that.
Mitch.