High frequency noise in multitone analysis

Hi, I am getting the correct response for multitone analysis in the low to mid-frequency range. However, in the high frequency range, the response is very noisy expecially for the phase response. I have read the user guide and I have implemented proper steps. The fact that I am getting a correct response in the low to mid frequency and the high frequency makes me think that I implemented the analysis correctly, but perhaps I am missing some sort of adjustments related to responses in the high frequency range.

Thanks!

Please attach the model for a better chance getting an answer.

Cheers

Falk