Accord CE7 98er – Vibration

Hello, I’m pretty little here, because my car has not made any noises for the last ten years, except wear. Now after just under 200 tkm on the clock, I commissioned my workshop: -Tahnriemen Set with water pump replace -new Bosch Zünkerzen Platinum Pro (before NGK?) install -air filter replace -oil change -new fuel -Filter insert and -Zündung set. The car now has more throughput, consumes about 1l less to 100km! I thought zuert Top, but: Now I have e.g. at 120km/h on the highway at approx. 3000 revolutions in the fifth gear so a vibration – which I feel in the steering wheel and also in the accelerator pedal. An employee of the workshop is test-driving and has confirmed it. You can also notice it in lower gears, only on the highway it sticks out more. It comes so from 3k rpm and only gets slightly worse at the hourly speed. BTW; If I then out of the workshop it is gone. My workshop means that there is no vibration?