When overtaking another car this morning the engine suddenly felt "dead" with increased vibration.

stopped at home checked that all tyres were true, exhaust fixed, rocking the engine from side to side steady in its engine mounts.

Started it again, when reving it got rough as if not running on all cylinders.

The engine is standard except modified idle speed control valve.

What could it be?


4/4 2 seater 2001 model