I have checked the codes. The only codes that come up with engine are secondary air pump related P0491 and P0492. I have read tons of threads about them and as far as I know secondary air is guided directly from the secondary air pump to exhaust ports to heat up oxygen sensor and catalytic convertor more quickly to lower the emissions during the cold start. In my mind it has no effect on the engine during the cold start. Or am I wrong here? The car has almost 300000km on the clock, so clogged secondary air ports are very likely the cause of these codes.

Anyway, during the holidays I did some highway driving and covered around 700km after reseting all the adaptations etc. Since the weather has been around 2-6 degrees I have not had any misfire problems during cold start ups, but I have been getting jumping revs (700-1100rpm) after cold start that begin about 10 seconds after the engine is started. They last about 10-15 seconds and then everything settles down withoud further problems.

I also bought a new oil filler cap just incase and tried to see what happens when I pull out the oil dipstic while engine is running. After doing it, the engine lost revs immediately and felt like it wanted to die. Also, it was easy to pull it out, no exessive vaccum in the crackcase I guess. After putting the dipstic back, everything was normal again.

Today I had a chance to film the car start up while there was 2 degrees outside, but the car had not been driven for 10 hours, so the engine coolant temp was still 6 degrees. You can see that during this start up the valve lift is set to 6mm and after the engine warms up a bit, the valve lift goes to the default value. No misfire, no major jumping revs this time.

https://www.youtube.com/watch?v=N9J1R6eejs4