Pretty sure its not that as the fault has slowly degraded and was intermittent, when it has its good moments, it runs fine with plenty of power and efficiency - 55mpg. It would be down on power and run like a mistimed engine.Check your camshaft phase timing is correct. You will need the timing locking tool kit, if you don't have one they are pretty cheap £15/£30.
I'm not sure on the 1.0L 3 potters but on the 4 potter it is possible to fit the inlet and exhaust cams the wrong way and still time it up and it will run with a few problems but no fault codes. Mechanically timing will be the same but the ECU will not understand where cams are in relation to the crank. It will try to fire at/near tdc exhaust stoke not compression stroke. As they run wasted spark they spark on both strokes anyway but only inject on the induction cycle so they still run.
You may also have a slack chain or it could have skipped a tooth. As the cam sensor has shown faults this is where I would continue.
So last night it ran as usual, this morning it ran terrible, the kangarooing has got really violent, it took two goes to pull away without stalling, and third time it needed clutch slip. It spluttered all the 15 miles to work. I'm looking for a wiring loom as something may be breaking down though that should show as signal intermittent type code. I'm going to re-fit the old coil pack and possibly crank sensor then wait for the code reader to show up.