My 1982 300sd is shifting late as in it won't shift untill i get the rpm's up to 3200 and then 4300 on the following shift. I've been messing with the bowden cable and the vac modulator adjustment in the past. I have plenty vac at the vcv on the ip because it's getting rid of extra vacuum constantly(this has started hapening fairly recently ... i cleaned out a line right in front of the brake booster where there was a blockage)

On the bright side since this has been happening i've got more power.My car's 0 to 60 time was about 21 sec and now i'd say it's down at least 5 seconds. I wouldn't have a big problem with this except for the car is allways at high rpm now.