XJ Rough Idle
My girlfriend's Cherokee has been giving her idle problems for awhile now. Most recently, she complained that while driving, it started acting strange and hesitating. She pulled it over, shut it off, and started it back up. She explained that when in park or neutral, the idle was very high (around 2k-2.5k). When she would put it in gear, the idle dropped dramatically. She said it idled very low, which I would guess would cause the "rough idle". This problem has been occuring more frequently, and even once while traveling about 6 states away from home.
Recently, I replaced the spark plugs with Autolite APP986 Double Platinum (recommended on JF). I also cleaned the IAC, cleaned throttle body, replaced crankshaft position sensor, and replaced the throttle position sensor.
I am wondering if these problems are related to the coil pack assembly? I have been debating replacing it, but it is pricey. Also someone on JF said that aftermarket sensors are garbage, which I have a hard time beleiving because many people don't buy Mopar sensors. Is it really nessisary to buy a Mopar sensor?
I would really like to get this resolved, because if not, then the Jeep will likely be junked for a chevrolet by her father, which neither her or myself are in favor of. She likes the Jeep, but doesn't like the reliablility because of how the Jeep reacts to this issue. Any help would be appreciated!
A few end notes:
Jeep: '00 XJ 4.0L AW4 NP231
Injector cleaner used every 1,500 miles.
Oil changed 50 miles ago, 5w-30 Penz.