Octavia VRS Tdi 2012 rough idle in morning. Glow plug light comes on, loss of power

Hello everyone,

I am at my wits end.

Octavia VRS Tdi 2.0 (170)

Car developed a rough idle and would sometimes cut out. Took to mechanic who diagnosed a failing High Fuel Pressue Pump. Said metal particles were in the fuel system. Had to replace all injectors, new HPFP pump, cleaned out the whole fuel system (twice). New sensors. Cost £2000 plus.

Car ran fine for 1 day. Next morning, rough idle between 1500-2700 revs. Could hear injector rattle. This was 1st thing in the morning. The coil light also came back on. Took it back to mechanic who said another sensor needed replacing. Replaced that.

Same routine, drove fine for a day. Next day, cold start in morning, car idles rough. Once it warms up it's fine. Cleaned the throttle body and EGR valve. Changed the fuel filter and car ran fine. Next morning same issue.

Vagcom gives an error code, (Will upload later)

I'm at my wits end, I feel like the mechanic is just replacing parts at random now to eliminate the problem.

I've noticed if I change the fuel filter the problem goes away, but then comes back.

Any one got any suggestions? I am at my wits end and just feel like torching it