The car is seems to lose power and gears don't want to shift, brakes become hard on 2004 Chevrolet Malibu

Power steering gets hard, car jerks and shakes. No codes come up no lights and problem is intermittent. Will not duplicate for mechanic. Been checked for vacuum leak and catalytic problems. Computer read outs are good. My daughter did admit to adding a small amount of PS fluid to brake system.

Asked by for the 2004 Chevrolet Malibu