MXDNJSport

I've been chasing down a low idle issue with our two XJ's. We have a Sport and a Limited, both '01, 4.0L and 4WD. Idle speed on both is around 600 rpms at operating temp, but steady. On both I've: cleaned the throttle body and IAC, replaced the spark plugs with NGK's (ZFr5N 3459), and searched for vacuum leaks.

On the Sport, I replaced the IAC with a Standard AC176 after the cleaning did not have an impact on the idle speed. So before I spent more money on replacing the Throttle Position Sensor and the MAP sensor, I checked the fuel pressure yesterday. On both, the pressure was 46psi from cold start to warm up. A little low to spec but within tolerance. To complicate things a little more, the Sport threw a P0432 code for the second time in two months. I replaced the oxygen sensors around the rear pre-cat yesterday as well. That had no effect on the idle speed.

Is the fuel pressure my issue? Do I go ahead and replace TPS and MAP sensor? And should they be Mopar parts or are other brands ok?

Thanks for reading.