I have 2000 xj. It has the 4.0, four speed auto.
When I go off-road, then drive it normally, the engine starts misfiring and stalling like crazy, it would not go over 3000 rpm.
I learnt about the heat soak thing, I rapped the six injectors with some thermal tape. I also replaced the spark plug, cleaned the throttle body and the injectors. What I don’t understand is when I stop the car and let idle, nothing changes. But when I restart it, the problem goes away for like another 2 minutes. One thing worth mentioning, even when it is not misfiring, it rough idles with the tachometer moving bits. Check engine bulb is out, I believe it is burn. Some guy told me it is the CPS, but I want to make sure because where I am from, parts are kind of nightmare to find and pricy.

 

Get an OBD code reader and see if there are any codes.

Heat soak only relates to hard starting, and only one injector at that.

Check for loose electrical connectors.

Check O2 sensors- how many you got?

Might be a "closed loop" issue which suggests O2 sensor something, but get the codes read first.

 

Thanks man.

I’ve ordered an OBD reader and waiting to get it.
As for the O2 sensors, i have my cats deleted from the previous owner, so no O2 sensors.

 

I suppose you can see what codes you get (besides the 40 oxygen sensor codes) and see if something else is fixable, but 2000 uses both upstream and downstream sensor in fuel calculations.

I think you're going to have to consider at least welding a bung in there and putting in a upstream oxygen sensor or an oxygen sensor simulator. I had a bad cat for years and performance didn't seem to be affected (other than engine codes, and consequently failure to pass inspection), so you may get away w/o having a downstream sensor.

 

And is this somehow a California XJ, or did it originally only have 2 oxygen sensors (EUR or FED)?

 

I’ll see how the codes look once i get the reader.
it is a GCC XJ, I am from Saudi Arabia
And that’s why I haven’t got my reader yet as well as why parts for these things are hard to find but you wouldn’t believe the cult following for these jeeps here. I just bought mine less than a month ago and I just can’t wait to drive it every chance I get. Love the thing.