1995 Jeep Laredo Overheating?

In my 95 Grand Cherokeei have replaced the waterpump, radiatior, thermostat, and clutch fan. It was running at about 250 degrees, but it didn't seem to be that hot when I got out of it. So I put an addative in the radiator that was supposed to make the car run cooler and it worked for a few days but then today I drove about 15 miles and the temp was about 215 no hotter and when I got home fluid came out of the cap like it was overheating. Oh I also replaced the radiator cap with a new one which was 18 lbs. (What was on there). I hope you could shed some light on my scene. Thank you.