Audi A3 cold start problem 🙁

Hi gents, recently had a tandem pump changed also lift pump now experiencing a cold start problem never had a issue before the pumps was changed I've had lots of parts changed since this problem being told it could be this and that, parts changed so far are.
New tandem pump
New lift pump
Battery
Coolant sensors both of them
Fuel temperature sensor
Vacuum pipes
Turbo boost pipe
Glow plugs
Starter motor changed last year,
Reason for the tandem pump being changed there was oil fuel filter housing also in the tank, this was drain and cleaned out also fitted a fuel filter with a new lift pump, sometimes it starts first time on the button and nextday three or four attempts would really appreciate if someone could help with this matter, it's been on diagnostic with no fault found
Kind regards Danny

Even though the the battery and starter motor have been changed, I would still start by having the cranking speed checked.

Thanks Crasher, can I check this myself with a voltage meter ? Kind regards Danny

You would need a diagnostic system that can show the engine speed whilst you crank the engine over with the injectors disabled so that is does not start and keep going for around 30 seconds or more and you need to see a minimum of 280rpm. When done, you would need to clear the injector fault codes you will have generated.