Abs/brakes acting up

I have a 1997 Buick regal gs with 122000 miles. On and off for the past year my abs, brake, trac off, and service vehicle soon lights come on. When this happens it almost feels like my breaks won't release. If I press the brake pedal down all the way, I hear and feel a grinding noise then it will run more smoothly. If not, the car won't even idle forward. Then after a block or so, it will jump as if something is releasing and it will drive fine. Please help me with this! I am hoping it's just a sensor somewhere instead of something more serious.

Thanks!

Sounds like the check valve to the booster has gone bad. Any DTC's? A full ABS scan may be in order!

No codes. Also since it has gotten cooler it's not happening. It's only when it's hot outside.