E90 330d injector questions

I suspect one or more of my injectors to be leaking but this is based on the symptoms and what i've managed to read up online. This is my first diesel car so please be gentle if my questions are a bit newby'esk.

Car is an 07 330d (pre-LCI)

Symptoms are a lumpy, almost misfire type idle on cold startup only. Severity varies from day to day.

I would appreciate assistance with the following:
1)Are there any other symptoms of leaky injectors?

2) How can it be accurately diagnosed? I.e. are there fault codes stored?

3) If there is 1 or more leaky injectors, is replacement the only option or cam something like ultrasonic cleaning help as well?

4) who in the Joburg area does ultrasonic cleaning?

Apologies if this has been covered elsewhere. If it has, please point me in the right direction

Thanks in advance guys