Hi,
Visually I can see that the fourth peak you are getting is because it is the local maximum around the location of that peak. Here I suggest setting the MinPeakProminence instead of setting MinPeakDistance because setting MinPeakDistance finds the maximum value in signal and ignore all the peaks within MinPeakDistance range. In that case achieving what is required in the question is not possible. Instead setting MinPeakProminence can ensure that the value is not dropping too fast around a peak.
