Possibly ETM that is directly affecting air flow.

It would make sense that if the O2 sensor is (falsely) reading too lean that the system would richen the mixture in reaction. Maybe try a new O2 sensor?? Also, have you connected a fuel pressure gauge at the injector rail to make sure the pressure isn’t running too high?

I rebuild the ETM as it was creating several codes related to faulty ETM, and throwing it into limp mode. The engine had a rough idling and strange lambda sensor readings (reading extremely lean at idle, actually running super rich). After rebuild is it still creating error codes, and limp mode. EC...

I went on FCP Euro and saw that a replacement solenoid for an 01 is the newer style connector that you mentioned. They give you two red wires and "seem" to say , tie them into your existing wires and go. Its just a solenoid, maybe it doesn't matter which way they are hooked up. Years back ...

You could try using one of the 9V batteries and connect each side to each wire and see what happens. Volvo used to sell a lead to do this, but now just include it with the CVVT replacement solenoid: https://www.volvocarstorontoparts.ca/p/Volvo_2002_V70-XC-24l-5-cylinder-Turbo/Engine-Variable-Valve-T...

Hm. I have gone through a similar issue with an 02 XC70. Never got to the bottom of the issue as it is not my car and access is hard to come by currently. I changed the solenoid (although it did not show any issues), checked the cam position sensor and it was ok. The car had a timing belt fitted not...