Grab the big plastic pipe that goes to the air cleaner then splits in two and turn it upside down. You'll see where it (and two others) go.
It's routed to the TCV (Turbo Control Valve) to regulate turbo pressure.

Sounds good keep us posted. My ETM is being weird too.

So this problem only seems to happen when the car sits overnight and the car is way cold. It's been pretty cold up here lately. I have not gotten and ETS light at any point yet. Pulled the module today, date code of 03, not particularly dirty but a lot of condensation on the back of the plate. Hopin...

Have you read up on ETM issues? Reason I ask is that they are not always plug and play. If you have the exact same part number you might be OK.

With the ignition off, disconnect the MAF sensor and try and start it again.

I using an elm327 interface with whatever software launches first. Yes normally I will get a reading for throttle position without an issue with this setup.

P0121 is the front or rear potentiometer on the ETM. A test you can perform is to cycle ignition to Pos II then listen for the ETM's cycle which is a humming noise for around 6 secs after ignition on then it switches off with a clicking noise if the engine isn't running. The above test only confirm...

'99 Volvo S80, 215K miles, yellow badge'd ETM. When I started the car up yesterday it refused to accelerate anything beyond 1800RPM and would misfire on cylinder 2 & 3 at idle. Eventually plugged in laptop and pulled a P0121, which seems to point at either the ETM or the pedal module? The thrott...

IMO its probably not worth doing rings AND top end with the GM transmission and two turbos in there. Its a matter of personal preference I suppose. I would fix the misfire and see if performance and fuel economy are acceptable. 4 has low compression but might be excessive wear from being fuel diliut...

Bores might just be ovalized. You could gauge em I guess, how deep down the rabbit hole do you want to go haha.