I have an 89 190e 2.6 The car was driving fine about 2 weeks ago with just a little erratic shift from 2nd to 3rd. If I let off the gas and then pushed back down, gears shifted fine and the car moved along fine. One day I came out to go to work and all of a sudden the car shuddered a little after shifting into 3rd gear but I could still floor the gas and get up and go. Now the car shifts ok from 1st to 2nd but when it goes to shift into 3rd and you are on the gas, the engine revs. It does shift into 3rd but if you are not just lightly on the gas in 3rd or 4th it'll slip. I can take the car down the highway at 80 - 90 and it'll go but only if you're light on the gas and gradually accelerate. I've been driving it like this for 2 to 3 weeks and it hasn't gotten any worse. Just out of curiosity I changed the trans filter and fluid and didn't see any metal bits in the pan at all surprisingly but the fluid did seem a little bit dark. May have just been old. It didn't make a difference, it acts the same. Wondering if it's a vaccum issue and if so what or how do I adjust it before I go looking for another trans?