I have a 1990 190EE 2.6 and just today, my shifting has been horrible. It seems like the shift goes immediately from 1st to 2nd to 3rd. And even if I put the gas pedal all the way to the floor it slowly climbs up from 20 mph to the normal speed limit which is 40 mph. I read several posts on here and they all seem to point towards a vacuum modulator, but I dont know where it is or what it looks like. If you have pics, that would be great too. Thanks guys.

or maybe it isnt a vacuum modulator, but something else. Not sure, please advise