Some questions

first off i think my CPS is bad it takes around 7 seconds of cranking to start every time but if i crank for like 5 secs and let off and without turning key off start cranking again it fires up in 1 t0 2 seconds and if engine stalls. and i start cranking it fires right up any ideas? and some times when i start it it revs up to 2,000 rpm's and then comes back down and stalls and when it doesnt stall it drops to 100 RPM's yes 100 and then goes back up to like between 500 and 700 what could cause this. i have just added fuel system cleaner might just need that just need time for it to circulate threw system.
and after we modified the front axle to be locked into 4x4 full time there is a clunking noise from front end me and my dad are thinking ujoints cus we beleive them to be origanal and te jeep is like 22 years old.

BTW it is a 87 XJ 4.0 5 Speed

Sounds like a typical Renix (87-90 4.0L) system to me. The extended crank time is because the computer has to see around 300 rpms before it will fire. As for the wacky idle, check out the "ReniX files" for a ton of good info. Check all the sensors etc and eventually you will get it straightened out.