I have an 88 Nissan 200SX (automatic) and it leaks brake fluid from the top of the master cylinder every time I step on the brakes. I can also feel the brake pedal fluctuate every time I’m at a stop and have the brake pedal down. The RPMs also seem to fluctuate a lot and I can’t get up to 25 MPH very easily. I have to step on the gas and force it into 1st gear. If I’m going up a hill, the only way up is to put in 2nd gear and pray I don’t get stopped halfway up the hill. Help anyone??!

your brake booster maybe bad, and you might have to much fluid in your master cylinder.

disconnect the hose from the brake booster plug it with your finger and see if it runs/idles better.