Volvo 850 engine stuttering at low RPM, not sure why?

[Krisemann]

Did you checked IAT values with multimeter?

Once it checks ok....we will proceed to MAP.

If it is ok....we will attack FPR.

If all of that checks out ok....then your brand new o2 is bad(it happens) or you have a vacuum leak which needs to be fixed and which can affect ALL related sensors and fpr.

I'll get checking soon, but I have to reassemble the car again as I have to use it. I tried checking the MAP but the pin couldn't get any contact with it.

Would appreciate a detailed guide on how to test the IAT, though!

[Krisemann]

Sorry for disappearing for a month - I simply haven't had time to work on my car. Now that I have though, I'll share the news. We had the old bolt machined out and fixed the intake manifold, as well as replacing the intake gasket and I ended up making my own gasket for the throttle valve. I've also replaced the IAT and MAP. The car runs very smooth now (it runs a liiiittle rough sometimes but it's barely noticable, so good enough for now), however the catch is that this does not apply when the O2 sensor is connected - the car runs very rough and stutterswhen it is. I've got no idea how to fix it and I've been struggling with this for almost a year now, so if I don't figure it out soon I won't pass checkup.

Sorry for bumping a month old thread!