Clio 1 – No power in 5th gear from approx. 80km/h

Hello helpful people, I’ve already used the SuFu and I haven’t found my problem yet, so I hope there’s someone who can help. Renault Clio 1 from 1996 1149 cc engine capacity 40KW/54PS code to (2): 3004 code to D.2 with test number: 76000A 4 I can record an acute performance crash in 5th gear. It occurs at speeds from about 80km/h and has the consequence that the car takes about 40-50 seconds to accelerate from 80 km/h to 100 km/h in lead At 100 km/h (downhill also 115 km/h) is however finished! The problem is apparently independent of speed, because in lower gears at the same speed problem occurs. In other words: In urban traffic and low speeds in the 5th gear the problem does not exist. Furthermore, the car jerks. It just does not bring any power. The gearbox also sounds striking and it grinds or knocks. Neither audible nor as vibration in the gear knob. iten of >50km/h you hear a quiet squeaking (from the feeling I say from behind) that stops as soon as I brake. Whether this is related I do not know but every info is certainly important. Please ask if you need more information! I hope someone can help me or tell me what I could test. Already he-googled I have things like: What would you type and above all: How do I test this?! I thank you all in advance and wish you a nice day, Tobias