If your fuel system is tight, injector seals are new, and there are no intake vacuum leaks or idle air valve hose leaks, then that should take care of any running issues. If there are still mixture issues, then you'll have to buy a rebuilt warm up regulator, as it's what controls your mixture when hot and cold. Also, make sure that your coolant temperature sensor is new and/or within spec at both warm and cold temperatures. K-jet doesn't allow for much mixture regulation at all, if any. Sometimes people will install a mixture adjusting screw on top of the fuel distributor like the later fuel injection systems had....such as in the W126. However, it's only a temporary band aid that compensates for a worn/non functioning warm up regulator.