Hi I have a 1997 Grand Cherokee with just under 300,000 miles. My engine light comes on once in a while and I am getting 2 primary codes. The first is # 1 cylinder miss fire It seems to be only running on 5 and once in a while the code is The one code is po301 and code po171 right rear or just fuel system lean. I don't think the cylinder is bad, It does not use leak or seem to burn any oil as I use synthetic and add maybe a 1/2quart between changes I change the oil every 7500 miles so a 1/2 quart in about 3000 miles. Not bad for 300,000. I am not sure what it is. I have new wires, and the plugs are about 6 months old, and the cap and rotor the same 6 months. I lack some power up hills but I believe it is the lack of the 6th cylinder. A friend who knows a little more than me said to put a new cap that uses copper instead of the one I have which is the aluminum. and I put Bosch plugs in, He said go back to the Champion, or the AC Delco that maybe it is running a little to hot, It does not always do it either, I have cleared the codes periodically with my computer, but not sure, The other thing is and I don't think this is it. I did take the cat out, But it was doing this before I did that. Any suggestions Thanks Brian