W123 m110 mixture adjustment

[mbenz280ce]

Ok I posted something similar to this not to long ago but I think I need to adjust my mixture on my mechanical injection (k-tronic I think). The thing is when I start it when it's cold it revs at around 1500-2000rpm but after it warms up it idles at around 500-700rpm. But it has a tendency to idle to low and stall at a light or whenever I have to stop. I'm 99 percent sure it's not a vacuum leak. Is it possible it's something else instead of the mixture. I was thinking maybe the fuel dampener or something. It has new injectors, fuel filter, fuel pump, rebuilt fuel distributor, spark plugs and wires. This is driving me crazy trying to figure it out. Any help would be appreciated