heelp.. 1986 W124 randomly stalls!

[humpy]

Hi All.. throwing my self on mercy of the forum.. I am in Australia, and my 96 yr old father has a w126... gearbox blew and fixing it ( on the cheap) has blown out to to over 12 months due to my other life pressures... he is about to drop off his perch and the Merc was his baby...so I decided to grab a cheap 1986 300E of nearly identical color and spec for him while sorting out W126 which has other numerous issues i have found anyway.. dont think its a keeper... W124 had a few teething probs but over all, after a bit of work is a really nice car!! my last remaining glitch is that after it sits idling for 5 to15 mins it simply stalls!.. for my father ( who will really only be driving it to the local shops as he is too decrepit to do much more, is still a worry as he might get rear ended/ sideswiped etc... the w124 had a weird issue where it would simply die randomly ( first 500km after buying it ran 100% perfect)... so i grabbed the ignition module from 126 and swapped in.. no longer have the random "sudden death problem" but still have this now latent issue... I thought was mainly caused by low idle ( 450 rpm) and fiddled with throttle cable to have it idle at 1000rpm for a easy ( albeit improper) fix for next few months... BUT after 5 -15 mins idling it still dies,!! have unplugged the um air/mixture controller plug?.. unit in front of intake under aircleaner ( that made it rev higher and last longer as a random experiment ) but still same prob... as its a 1986 no obd2 plug to diagnose.. really want to give it to him next week before his birthday.. he isnt now up to driving much at all , but at least seeing it in the driveway will give him joy.. totally stumped and on very slim budget... any ideas"?

 

[NDavies4]

Hi Humpy, you get anywhere with this? Have an A124 from '91 that had similar issues - after many years of suffering I think I have it finally sorted