Suspected Variator Problem

[Potzy]

Hi everyone,

I've been lurking a while, doing some digging so I'm pretty sure that the problem I have is likely the variator.

Car is a 56 plate 1.6 Mk2 Focus, Ti-VCT Petrol with 106k miles on the clock.

Around 80% of the time after the engine has been sat for more than 15-20 minutes, I'll get a relatively loud tapping noise from the engine.  I recently installed a dashcam which caught one episode recently (I've adjusted the audio levels a bit so you don't get deafened by the 'Recording started' message) : https://youtu.be/n0xn7-PAF3E

I mentioned it to my local Ford garage who took a look and they weren't able to get it to happen reliably, so they replaced the water pump as it was starting to show signs of wear.

My fuel economy has dropped from an average of 38-44mpg to 34-38mpg, and whilst it's fairly subjective I think I'm down on power, especially when cold.  

Engine idle isn't perfect but not giving me any cause for concern, but when driving along at a steady speed with hardly any throttle on it does seem to hesitate/surge regularly.  Otherwise it drives fine, able to accelerate up to motorway speeds fairly easily.

Some other info that may be relevant:

- Cam belt changed at 80k, water pump changed at 100k, regularly serviced and using 5/30 fully syth
- Noticeable tapping within the car when driving, noise is weirdly more noticeable within the car with the windows closed, but it's always there
- Engine is on its 3rd coil pack.  One replaced at 69k miles literally on the day I picked it up from the garage, then a coil of cheap replacements followed by a genuine Ford coil pack at 75k miles and its been fine since
- HT leads replaced at 75k with after-market cables (Ford wanted £60 per cable!)
- Spark plugs changed twice, currently using NGK plugs at 1mm gap, engine barely ran/idled at the stock 1.3mm

All of that I believe points to the variable valve timing, but thought I'd see if anyone had any other ideas before I go back to Ford and fork out for them to do what needs to be done (Am expecting ~£750 here?)

Thanks in advance