I have an '88 300E that has been experiencing "flaring" between second and third gear shifts. When I went to do the adjustments to the vacuum module, I noticed that there was a small leak, so I had the module replaced. Ever since then, I still experience flaring, but after 10 minutes of driving, the flaring subsides and the trans shifts like it should. BUT, after another 10 minutes of driving, once the fuild is warmed up, the shifts are very harsh and at times violent.
After the module change, Dexron III and a half quart of AmsOil fuild were used. I have tried a few different combination of adjusting the vacuum module and the bowden cable, but if I take care of the flaring, the shifts once the trans is heated up are very hard. I drained the fluid combination out and replaced it with Valvoline Synthetic Dexron III. Same problem exist.
Any suggestions on how to get the trans back to normal shifting? Aside from the flaring prior to changing the vacuum module, it shifted great. When kickdown is engaged, all gears shift fine and crisp. I feel like I am fighting a loosing battle with the trans.