Hi SFG,
Yes that's right, while driving if the brake is pressed with the left foot while the right foot stays on the throttle the brake overrides the throttle and the car slows, power from the throttle is reduced, can't say whether it reverts to tick over or not as I released the brake prior to stopping, I do not drive in this way, I only found out this happened when I wanted to dry the discs and pads by operating the brake gently whilst driving, the brake overrode the throttle, hope this makes sense.
It definitely does it on both my mercs, I'm sure it did it on my roadster and plus 4, maybe someone on here can support this? (it is a few years now since I had a Mog and my memory is not what it once was)
I'm not suggesting that this is the cause of your fault, it was just another idea to look at.
