This is probably a technical question for the transmission experts:
Persistent problem on my 722.358 transmission. If I rev the engine above approximately 3,500 rpm the transmission starts acting up. Specifically for the rest of the driving time it will start randomly downshifting from 4th to 3rd and sometimes downshift even further to 2nd or even not engage to any gear at all... To go back to 4th I have to put it into N and then back to D. That will put it back to 4th but it wont stay for more than a minute or so. Then it will start downshifting again.
It won't stop doing it unless I turn the engine off and let it cool off completely like overnight. Then the next day it will drive fine again and everything is good until the day I take it above 3,500 rpm again...
Again as long as I don't take it above 3,500 rpm there is no problem. I've been driving it for a week or so and shifts great. So I am trying not to let it rev high but sometimes i need to lets say overtake or enter a freeway from the ramp and I have to be very careful to not let it exceed 3,500 rpm because then it will start acting up.
I tried disconnecting the electric solenoid but it did not make any difference.
I changed the transmission fluid and it didn't make a difference either.
Bowden cable is checked and operating correctly.
Suggestions?

Can you check the small micro switch on the bowden cable quadrant .

I'm not sure witch micro switch you are referring to. The only one I can see is the micro switch next to where the bowden cable attaches to the throttle but this micro switch is for the CIS injection system it is not related to the transmission. It works fine.

Is the bowden cable too tight? Have you tried slackening it? 4th gear requires the most fluid to engage the correct brake bands and clutches. If you have low fluid, low operating pressure, or excessive internal wear on the transmission, 4th gear is usually the first to show issues.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

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1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
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1991 350SD
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Its actually adjusted a bit on the loose side so no its not tight at all.