I have a '92 300e that seems to not want to shift up when cold.
The issue is not wanting to shift up when first driving. Seems to
sort of stick and not want to shift up past 20 mph. If I pull over for say 30 seconds, it runs & shifts 1 - 4 just fine.

If I let the vehicle warm up say for 4 - 5 minutes, or so it has no shift issues.

Could there be a vac leak issue ? Any help appreciated.