E196. What could be causing this code to appear

Question

My Ford Focus Titanium, 2007 Manual Petrol, has started to act eratically. Namely the Rev Counter has been dropping out at random points and violently kangarooing. Replaced the Crank shaft Sensor as this came up on diagnostic test. Worked ok for couple of days and then the violent kangarooing started again.

when lifting clutch the rev counter drops almost to point of stalling the vehicle, even with the requisite amount of acceleration.

At speeds of 20 mph or so, the car violently jolts and then rev counter drops out for few seconds, then another violent jolt brings it back to life. When picking up speed to 30-40 mph, there is a disctint loss of power under foot and progress seems inhibited.

The engine management light is permanently at amber.

Any help is very much appreciated, main dealer couldnt tell me what the code would point to.

Any help is much appreciated.