hello guys (girls if any )

after i gave up on the mechanics we have here, i only hope to find the answer to my problem here.

i have a 300sel w126 1990. when i step on the accelerator all the way down, without clicking the kickdown button, and when the rev reach the limit, the car won't shift to the next gear, instead it get stuck on the current gear and keeps connecting/disconnecting the rev.. like vvvvv---vvvvv---vvvvv

i hope you get what i mean,, simply the rpm goes to 6500 and back to 5800 and forth to 6500 ......... it only changes to the next gear if i lift my foot off the pedal a little bit.

and this happens on all gears except from 1st to second. note that its an auto trans.

any advice!

thanks

if needed i'll post a video of the problem.