W123 shifts fast, 300D, help!

I have a W123 300D-T with 200K miles on it, and all of the sudden, it seems to be really slow, and shifts really quickly. like before I even get to 30
mph, it has shifted all the way into 4th gear. I stomp on the gas and it will downshift but only for 1 second, then upshift again. This sounds like an expensive fix... Can anyone tell me what's wrong, and what needs to be done? $?
Darrell
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Could be a vacuum leak; the tranny i controlled by vacuum.
Check for a leak with a mity-vac. Also, clean out the banjo bolt; crap build up in there and the LADA is unable to swuirt in extra fuel under turbo boost.
The cable may need adjustint too, but you can't do that till you have the vacuum straightened out.
This shouldn't be expensive to fix.
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The transmission is given the throttle position by the rod or cable connection to the throttle linkage at the top rear of the engine. I suspect this link has become disconnected causing the transmission to "believe" the throttle is always closed. So it shifts up as quickly as possible.
The downshift you experience is from the electric kickdown switch behind the accelerator pedal - normal.
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