Car Tech forum: 1997 Jeep Grand Cherokee 4.0 dying when up to operating temp

The car started with a guy at his shop ran codes it kept comming up cam and crank sensor..ok they changed them ...then they cut open the cat-converter...and i dont know if they punched it out or not but they welded it shut.....then i got the jeep and took the crank sensor back out...was new ...cleaned it and put it back in...then still the same can drive till 210 degrees(normal operating temp)presumibly..so i took the distributor cap off ..it looks all new plugs,wires,cap,rotor,and cam sensor...so.i cleaned it up better even though it was new...cleaned cap terminals..rotor..and curved sensor plate...so i put it back...same thing!!! then my friend says try coil .(when they get hot on the block sometimes they break down)wasnt that...then i decide..check all the fuel beautiful pressure when normal and acting up.....so i put a coolant temp sensor in it....still same thing.So then we buy a remanufactured ecu.(computer)..then i thought it would b good..pluged it in the same damn thing ...my heart dropped.Then i was reading all these blogs for the last day and a half so i figured the computer screws..nope asd relay...nope...i checked the whole wiring harness shook all connections while it was acting up ...no difference...then i just brought it to another guy...and he has me convinced what i never really thought of!!!.he scanned it same codes as chrysler said ..crank and cam ..so what he determined is the timing chain got slack in it and when its cold it runs fine..when its hot chain stretches causing intermiting firing cause its not firing exactly on point when hot so computer gets a different reading and doesnt know what to do so it runs eractic...well i wont really know till 2 more days when he can check it out with and mechanics..orthonscope or summin...it determins exact readings from precise location...but ity all makes sense..but future will tell...this Jeep has been a nightmare..oh yeah i just replaced the differential..cause it was howling another common problem on these beautys...but i will up date this if i do happen to put the timing chain in it....but does it make sense to you?...any information would be usefull at this point......ok thankx ...mike......appreciate it....

1996 jeep cherokee 4.0 limited SE A.
i have the same problem. runs fine upto operating temperature then cuts out. shuts down. then starts when cold. i've run a diagnosis and came up with the code 12 55. as far as i've found 12 means battery disconnected in the last 50 key starts.i cant see how thats a problem. and 55 means diagnosis finnished. so i'm wondering if or how u fix your problem. thank you..