Need cure for Self revving

[3rdgear]

Morning guys, is my 3rd post here regarding this
Issue as I'm not having much luck on getting it fixed,
So I've taken out the Cobb and problems seems to
Have calmed down a lot but it still happens few times a day
During nutual, it revs on its own and tho it's only slightly
But it bugs the hell out of me knowing there is a problem.
2 workshops and a dealership has looked at my car and
We have ran out of solutions so I'm coming back here hoping
I'll find my M wizard.
So far, I've replaced all injectors and spark plugs, cleaned
The throttle body along with the whole intake system and refresh
The latest software, checked for vacuum leak and cylinders.
Was also told it's not the fuel pump as the car drives fine otherwise.
Gas I'm using is Ron 98 and I doubt it's due to that as
Other 1m is using the same without problems.
Mods I have now is forge intercooler and ak mid/muffler
The self revving is very unpredictable, can go for hours without
Happening.
My warranty will expire soon so if I've missed any check points,
Pls educate me.
Lastly Can it be due to cobb tho it's be unmarried, could it have damaged
The computer or messed up my settings permanently
Thank you, you are my last hope

[RimasRS]

Valve carbon build up?

[robertm]

Sounds a lot like a vacuum leak to me. First thing you can do is get some carb cleaner and test all hoses and fittings. If that doesn't produce any results, get a scan tool and analyze your STFT numbers. This can be helpful in diagnosing a lot of issues. To involved to write here but look online for something like 'Fuel Trim vacuum leak diagnosis'.

Frankly I'm shocked the BMW dealership can't figure this out. There are a limited number of potential causes.

[3rdgear]

Tks robertm, I checked it out in YouTube,
The scanner looks pretty advance, is it something most workshop will carry, I'm sure the dealership would have used it if they had it huh

[woltersjason]

My Toyota does this as well, extremely annoying but only does it after its still parked and warmed up. I don't care enough about the car to try and fix it though lol