Bizarre shifting pattern 1984 Mercedes 300D automatic

Sounds to me that your transmission is put itself into what is call (Limp Mode). This happens when the transmission fluid in the trans hydraulic valve body located on the bottom and in the trans pan are not within the parameters of the transmission computer. You can remove the trans pan and gasket to check for metallic material in the bottom of the pan. There is normally a strong magnet in the pan catch the material so I can't move freely through the transmission itself. It only takes a very small piece of foreign material to stop the flow of the valve body fluid. I would first take it to somewhere that had a automotive diagnostic scan tool that can read transmission codes to see if there are any active codes. Next you can drop the transmission pan yourself and look for material in it. Basically do a visually inspection and service the transmission fluid, gasket, and filter. Remember, all a automatic transmission is a extremely complicated fluid pump. If its pumping trans fluid properly it's probably working just fine. Been when the trans fluid gets hot, scorched, and stops moving. It will not work. Hope this helps

If it wont shift at all, its very likely computer related. Its unlikely it could be vacuum because of its age. Their is a computer for newer trans and sometimes some of the components can fail. I once bought an accord that lost 2nd and 3rd due to its computer, shifted great after i hit the junk yard. If it shifts hard though, solenoids and valve body gasket.

You are right about the shift pattern. Reverse is hard left and up.If your gears are locked up, you'll probably have to remove the side cover and reset the shift levers to their neutral position and then slide gears around to put it back on. With it back on the shift levers should point up toward the car floor. 3-4 is the shift lever closest to the engine. 1-2 is the middle one and reverse is the one closest to the back of the tranny. Check all your swivel points for looseness. If there is any play then you'll have to bush it out or you'll have trouble getting it to shift into gear and stay in. I used some old copper pipe to make bushings on mine, because it used to jump out of gear.
To properly attach your shift linkage, put the shifter and the trans mounted shift levers in neutral. Loosen the locking clamps so the shift rods slide freely. start with the reverse lever, which is the inner most rod on the shifter and tighten the rod nut against the swivel. Then tighten the lock nut. Do the same with the 1-2 rod on the middle rod on the shifter and then the 3-4 which is the outside rod . This should set you up, according to Chilton.
They note that if the tranny is 68 Camero Muncie the shift rods need to be shortened 3 complete turns of the lock nut.
Hope some of this helps.

you may not have trans problem at all. most of the time your motor mounts when worn out or broken can cause a hard ****. Put your car into gear with your foot on the brake and give some gas abrubtly and see if your engine jumps. do the same in reverse. remember to use the brake and have your hood open to see if your motor jumps.

drain and fill trans with fresh fluid
trans may have to be rebuilt

sorry

What you need to check is the transmission release bearing because if there is a clearance on the release bearing you will encounter this problem and also check the transmission oil.

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change fluid in trans add lucas for trannys let me know if theres metal in the pan or if you have trouble tell fixya bout me ok

When was last fluid & filter change?

Check the trans fluid level.  Is it dark and burned?  

shifts off electric servo controlled by cars computer , see trans guy you can trust could need service ,oil and filter changed or part , like i said see one you can trust .