serialpyro

Hello. On my 200k 2004, since i own it (one year ago). I have lot of trouble and lack of power with delirious value from the first lambda changed this summer. Lftf is always changing. Very negative as if i was very rich and very positive in few seconds as soon as I accelerate. I am starting to believe more and more in an air intake on the exhaust manifold. Have you ever heard of worries like this ? The screen shot attached is with tempomat and so regular speed. Thank you very much.