I'm having same issue with my m103 in a 1988 300CE. Seems like the transmission is shifting in a big delay mode. could just be the modulator is in need of adjustment or the vac lines need replacing. The trans mount is in need of replacing due to motor oil on it over the last 18 years.
My trans problem started with a short delay when going from second to third and now it's getting to the reverse gear too. Reverse is hard and I can feel the driveshaft picking up the power transfer late and when it does it's not smooth.
I'll get the modulator vac line looked at and also replace the trans mount to see if that helps, it should.

The shifter itself seems fine, it's definitely at the modulator. I dont think its the gear valves themselves. The delay I'm talking about is when after shifting the actual shift takes longer than it shound and when it does finally shift a second later its jerky and the motor is working overtime.

Recently changed the trans fluid and motor oil and all filters. Replaced the fuel relay and checked the plugs. Replaced 02 sensor with the expensive model. Been running only chevron with techron supreme for 6 months. Replaced exhaust with stock center resonator and custom 3" pipe to rear muffler. Just passed CA smog.

Sorry for hijacking this thread.

Thanks
Jason

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1988 300CE 120K RIP(Midnight Blue/Parchment)
1987 300E 202K (Arctic White/Palomino)


Now I see the secret of the making of the best persons. It is to grow in the open air and to eat and sleep with the earth. ~Song of The Open Road