W210 E320 CDI weird MAF readings

[Hokmabrio]

Hello. I have a w210 e320cdi which gives me a headache. I checked the cables(they were fine), and change the MAF sensor but i still got some kind of a weird reading.
At idle i got around 300 mg/hg (i don't remember the unit correctly) and when i'm at around 1500rpm i got around 400 mg/hg BUT when i release the throttle it jumps up to around 600~650mg/hg for a second. Is it normal? If not what can cause this issue?

Any help would be appreciated.

 

[supernoodle]

I guess the unit you are talking about is mg/st or sometimes written as mg/hub.
You need to monitor EGR valve position also as what you describe sounds like EGR operation, which would normally be open at idle, momentarily closes when you lift off. That I would say is normal behaviour, so hope you didn't change the MAF just because of that.