I have noticed a few posts regarding Jeep Liberty KJ 2.5CRD that have a rough idle or stumble and cut out at idle. This can happen whether motor is cold or hot. My Jeep was doing this and changing the TPS (Throttle Position Sensor) cured the problem. The change also cured a flat spot just off idle - at about 1000RPM. It is interesting to note that the ECU did not display any error codes indicating a faulty TPS. The only thing the scanner picked up was a normal fuel rail pressure that dropped to a low pressure as the motor idle RPM dropped. This was messing with the ECU's logic circuits. I did change the Fuel Pressure Sensor before I changed the TPS and the change had no effect on the erratic idle and the cutting out.