If I were in this situation, I would check to see if the ECC unit has stored any error codes and make a note of them if so. Then I would clear the error codes and see which codes are repeated. I'm guessing you've already checked the cabin filter is clean (or removed) so it can't block airflow. Anoth...

That image looks like a Pierburg turbo control valve / boost control valve / solenoid I got from a '98 in the junkyard a couple years ago. If you search for TCV or BCS on this site you can find more info about it and how to hook it up to the wastegate and other connections.

I usually use a brass bristle brush with a short handle to scrub off corrosion from the brake rotor and the inside of the wheel. I like it because it can live in my tool bag.

Sweet looking 5 speed 240
https://bringatrailer.com/listing/1992-volvo-240-14/

In one of Robert DIY's videos he mentions to check for silicone oil seeping around the piston -- that's a sign of a failed internal oil seal.

On my '97, there was quite a bit of red power steering fluid in the boots covering the tie rods. There is a picture here: https://www.matthewsvolvosite.com/forums/viewtopic.php?t=58194 I have been monitoring the fluid levels weekly since then and topping up as needed with 'high mileage' ATF fluid, w...

My 97 gave this code when the pipe connecting to the roll over valve was nibbled by a squirrel or some other creature. The roll over valve (at least on the 97) is near the fuel filter at the rear of the car.

viewtopic.php?p=369977

Here is one that made me laugh... owner/parent describes drawbacks:
https://roanoke.craigslist.org/cto/d/ro ... 89491.html

Good luck and let us know what you find. I'm no expert on engine control systems, but my understanding is that the ECU reads the ECT sensor among others to make adjustments to the amount of fuel injected. Additional info is available here: https://www.volvoclub.org.uk/tech/service/850/EngineTheoryOp...

You could have high resistance connections at the battery, starter and alternator. I like your approach of checking for excessive voltage drop and/or heat at each one. I have an 850, which is different, so I'm not familiar with the resources available, but a search shows that one good spot to read u...