1994 jeep awd 5.2l park dont engage and makes clicking noise when

Immediate fix. Turn engine off then put into park.

This going to sound strange but I bet your blower also not working when the happens. Your key is still in the "start"
position but not forward enough to engage starter. When this happens:
Slightly turn key back until it clicks into the run or on position.
It should do this all by itself when you let go of the key after starting, but as things age and wear they can stick.

Have it scanned before you do anything else. Could be the transmission or cable or park neutral position sensor. Scan it first

take it to a jeep repair shop - you need some serious work on the gear box/transmission.

Rock back and forth , take it out of AWD , Put parking brake on shift into Park .

open phone book to yellow pages. look under automobile repair-transmissions.
there is no magic button someone can tell you to push, you need a transmission repair and you
are not going to do it yourself. the transmission fulfilled its design life 7 years ago. you can most likely get a jeep 10 years newer for what you will spend on a transmission rebuild.

Without the benefit of actually getting under there and looking/listening, the best I could offer is a guess. Neither your front or rear differentials can make noise when they are not turning. However, if you see either driveshaft turning when the Jeep is in gear and standing still, I'd suspect that you either have broken gears in the center section or a broken axle.
If the noise is coming from the transmission or transfer case, you will need to find out why. Internal noises from either generally require replacement or a rebuild regardless of the original cause.

It should be an electronic problem Scan the transmission and post the codes

The noise is the tooth engaging your parking dog in the trans. think of a big gear with square teeth and a plunger that fits into the valley of the gear. not always does the plunger hit the valley so when you roll a little it comes off the high point and settles where it belongs

do you know ware the clicking noise is comming from? maybe relay? maybe bad sellinoid? the sellinoid is my guess.

1. I would suggest that you engage your 4WD while you are in full stop and/or safe range of 5mph, however as claimed by the local dealers your vehicle is capable of engaging even while driving. Engage your 4WD while moving only when necessity requires.
2. That clicking noise while turning extreme right or left would be the birfield of your axle and would only mean your front hub is still engage even though you have disengaged transfer case.
Have your front hubs cleaned of old lubricants or grease due to non usage. dont use grease as lubricants, use thick oil such as gear oil or silicone oil. and use your 4WD every now and then.

Do this first then check if you still feel somtehing is loose on your suspension and others.