Hey so as the title says I am new to the xj family. I recently bought a 2000 cherokee classic. It has 212,000 miles on it and until now it has been running fine for me. I am not sure of the history on the jeep. I am primarily using the jeep for 4 wheeling. I have pieced together a 3 in lift and got some 31 in maxxis mt's. The problem I am having is my engine seems to mssfire when I am starting it after it has already been warmed up. I sure there are tons of reasons that could cause this but I am looking for some input. I recently changed the oil and added a quart of lucas leak stopper and replaced the plugs with bosch plat plus. I also currently dont have a muffler on the jeep. Could either of these have to do with my problem? It starts cold everytime without any problems. I am installing a muffler tomorrow hope that will fix it... but let me know what you think. Thank you.