93' 190E 2.3L hesitation/stumbling

[rrollo]

I purchased this 1993 2.3L car 123K miles. Here are the conditions:

When first started and cold the idle is great very little or no stumble on take off. If driven on the freeway (warm to hot) then the idle will start to wander (good a few seconds then drops for a second) when you city drive at stop signs (like a miss and giving throttle at idle doesn’t always correct it)(sometimes it idles just fine and only has the stumble on take off?)

Once warmed the hesitation/stumbling usually gets a little worse off the line. Never stalls but acts like a miss and misses more when you first take off hard again (still in that 1000-1500rpm range.) Afetr 2000rpm it drives well and always cruises great at any speed.

Occasionally when under full throttle on a down shift the engine seems to go flat around 4000rpm and just hangs in 3rd gear until you let up the throttle and it up shifts to 4th and you have power again. That seems to be better since the vacuum lines were replaced to and from the idle speed seloniod.

Any ideas for this vintage CIS Mercedes? Thanks