S40 2.0t jumping idle when cold

[Filipd]

Hello guys i’m new to this forum but not volvos.
I seem to be having an issue with my s40 2.0t
The car is a 1998 model so phase 1.

The issue seems to be the cars idle when i first strat it up after it was sat and i cooled down fully. When i start the car in this scenario the idle is at around 1100 rpm it then starts to climb ever so slightly to maybe 1200 and after that it starts to jump from exactly 1200 to 1800 rpm until the car gets warm and then starts dropping until it is stable at around 750 or so and runs like a dream after that. There do not appear to be any power issues as the car flies when you put the pedal down and feels like it has more than 160 hp. I have been looking for someone with a simmilar issue but can’t seem to find a match. I have replaced the crankshaft and camshaft position sensors aswell as the fuel pressure regulator which are common faults that tend to go bad with theese cars. The car doesn’t have any lights on the dash that would indicate a fault so if anyone would happen to know what the problem could be or what to check it would be of great help