[1990cherokeenc]

My girlfriend has a 1990 cherokee and recently it started having a little problem. When it warms up to about normal temp it loses power and wount go above 2000 RPM. It bogs and backfires when you try to accelerate. It rarely cuts off but when it does it always starts back up. When it cools back down it runs fine. Also the water in the overflow is boiling. What should I start with.

[LCFRJEEP]

I think your thought process is that the two issues, the back firing and the boiling coolant in your overflow bottle, are one in the same issues. Start by trying to solve one at a time. I would see if your XJ is equiped with a TPS sensor (Throttle Positioning Sensor). Then I would probably change your Oxygen Sensor. Then mabey your EGR valve. As far as your boiling coolant, I would try flushing your cooling system (radiator, heater core and all lines), if no relief, try replacing your water pump and thermostat. Also make sure your electric fan is kicking on periodically. What is the temp showing when your over flow bottle is boiling over?? Let me know and good luck.