I have an issue that started shortly after a (possibly dodgy) mechanic did some work on my brakes.

When accelerating, sometimes, the revs will drop to idle, as though the clutch had disengaged the engine. If I pull my foot off the throttle and put it back on, it re-engages and accelerates normally. It happens mostly when at 30mph, and I know the car's history is mostly around town.

I know the car is fly-by-wire, so the throttle feels into a unit that sends data to the engine's management unit rather than being a throttle cable. Am thinking to replace the unit the throttle is connected to, but I don't know what it is called?

Any other ideas? Also the cruise control stopped working at the same time, annoyingly.