3L Tdi transmission.. 5th gear

Servus, I’ve already read some gear entries here to get to know what’s going on with my car. However, I haven’t discovered anything like this yet. The following situation: My 3L ran perfectly when it gave me the automatic insertion of the 5th gear in the Eco mode a violent jerking and “beat”, the gear went in idle mode by itself and then reacted to nothing. Only after switching off the engine and ignition, switching levers on stop and start again – but when the 5th is again reached the game starts again from the beginning. I have since only run in manual mode, and switch only up to the 4th. Consumption is at about 4,5L, and that at 90km of road and in average 110km/h. In addition, the reverse gear tends to jump frequently into the idle course, and quite rarely the gear can be read the 4th gear also and switches independently – under no consideration of the driven speed – already down to the 3rd. Now I was told “Galebre” to let off the gear wheel” due to the 5th wheel of the clutch.