Inlet Manifold Failure.

[wildchild]

Hi guys bit of a strange one here and i prob know the answer. 06 plate z19dth and i know the inlet is goosed as i changed it about 6 years ago and now these swirls have gone...Now bear with me ( i have got another replacement that im fitting this week when the timing belt kit comes as thats due) ive had a bit of an hissing noise for the last couple of months but over the last couple of days ive been hearing a different noise which turns out to be an injector noise BUT its coming from swirl flap 1 area but no fault codes, only slight drop in performance but i expected that and no excess smoke only black cloud when i give it some, and this injector noise is ONLY present when i rev above 2k so ive been driving it below 2k where possible until i can get on it later this week. my question is, would there be any other problems that could cause this before i start stripping it down?.
TIA Gaz

[Dog_Book]

Until you check the whole engine and pipework for leaks you won’t know