So from my self repair experience you may have a dirty Throttle Body, or possibly just broken altogether. It’s easy enough to diagnose yourself, almost as simple as replacing a headlight. You’d start by finding the air line that goes from your air filter to the top of the engine, in between along that air flow tube you should see an aluminum body with what looks like a body pack attached, remove the air flow tube to expose that being careful to not let anything fall in there and check if the valve (brass spinning disc that controls the amount of air flow allowed into the engine) is filled with gunk or if the aluminum body inside has any gunk that could impede the free movement of the valve. if that is the case DO NOT FORCE THE VALVE TO MOVE, this could ruin some calibration with your acceleration that would take recalibrating. You’ll want to find a throttle body cleaner to use on that and very carefully with minimal movement to the valve itself spray on the cleaner (make sure its absolutely meant for throttle body) let it sit for a minute and procede to carefully scrape that gunk as clean as possible. This should fix the unstable idling.
As far as the stiff breaks, it could be its own problem that seems to be connected, id recommend check your fluids and bleeding the brakes out of precaution and all comes to worse find someone to diagnose your calipers and abs pump which may be causing the issue.