Originally Posted by i6zombiejeep
Thanks for the advice! I will try all of that and look into getting a Mopar sensor if this one continues acting up. Good thinking with the caulking, I actually have some of that stuff.
You're welcome and if you pin the cable by the crank sensor to the far left outside with a wire tie or bungee it's easier to get the bolt/metal shield/sensor in. Also disconnect the neg cable on the battery every time you disconnect or connect a sensor.
Make sure all your grounds are good/clean including the one on the fender next to the battery and the 3 on the engine block. There's 1 on the oil dip stick tube bracket and 2 on the coil bracket studs. One of these grounds on the coil studs near the 4.0 motor mount grounds the PCM which in turn grounds all the sensors. This rusted/oily PCM ground on my 96 4.0 took out 2 PCM's and a crank sensor. Learned a harsh lesson on that one.
When purchasing a Mopar crank sensor you can save some $ by buying online rather than the dealer. I don't have the 98 parts list but it looks like your 98 4.0 takes a Mopar 4897321AA according to the below sites.
There's a lot of real good info in the dirty dozen link in my signature written by ZeeJay. If you haven't done it yet clean the IAC and there's a link on how to do it in his thread. Good luck!