Wierd revving!

Just got the car (R52 MCS) back from it's MOT and went out for the day (great day for the roof off). Last few corners from home and upshifted on the way out. Heard a noise I can only describe as dry crackling for a few seconds. From then on under mild acceleration the revs spike momentarily without the car accelerating to match the revs. All very odd, and upsetting.

No warning lights, still changes gear and works (reversed onto the drive fine), but something isn't right. Wasn't pushing hard either.

Anyone else seen this before to give me some clues as to what's gone wrong?

Niall

- - - Updated - - -

So after 20mins went back out. No obvious oil leaks or bad smells. Car started fine. Revved fine in neutral. Ventured out on the road. Drove fine. Wholly linear acceleration back in charge.

Whilst I'm happy with 'turn on and off again and get on with your life' for home electronics; not sure I'm comfortable with the same attitude to prized cars. One to keep an eye on clearly.

Turns out an exhaust hanger was perished and the other was missing (which probably explains the dry crackling noise I heard a few months back). Also turns out we may have the wrong exhaust(!) as the garage couldn't get it to refit with new hangers without a bit of butchery!

Strange