On the "new to us" 1996 e300 with the 4spd hydraulic tranny and 145K, we have no converter lockup- in any gear. Yes, I know "for sure" that it isn't locking up as any acceleration in any gear causes an increase in rpms on the tach (until an eventual upshift, at least to 4th.) I have also noticed a hesitation between the 2-3 shift as well. It runs at 3K at 60 mph on the freeway and any push on the pedal at all causes the tach to climb and the engine speed to increase. I'm very worried- because the PO couldn't tell us when the last fluid/filter change was. There are no tranny codes (but then there probably wouldn't be any since she's a 96.) any thoughts?

Please advise, and as always, thank you all for any help!!!