Please Help : Normal Or Vacuum Leak ?.

[Leigh_bullitt]

Hi All
I have a 2020 Bullitt and noticed something while the car was idling.
if I press the brake, when I release the rpm’s fluctuate before settling down again.
I connected the Sctx4 scanner and when idling everything is perfect. Measured lambda is bang on 1.00. But as I pump the brakes the readings drop to 0,83 which would be a rich mixture.
I do have some intermittent problems with the car in that it sometimes runs great and other times a little off.

is this normal ?.
or could I have a vacuum leak at the brake booster ?.

thanks

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[Nightmonkey]

Not sure, but I have not yet been able to observe what you describe.
Should actually be the clutch, because the engine control assists you when driveing off to prevent stalling.
That's why it's so easy to drive off without the accelerator pedal using only the clutch.
Is the clutch involved in your observation?