Drop-outs from 175 km/h: LLM???

My 1.8 T 180 hp no longer has a strong start, but has no more power from 175 km/h. However, this does not express itself in an unbearable jerk, as if it were not going through enough fuel. I think it could be the air mass meter, a clogged fuel filter, a cracked line. I have read out fault memory, there is nothing left. Have you experiences or a tip so that I don’t have to be a friend, that will be too expensive for me… Thanks already now!!!!!