So... my 2005 Volvo XC90 V8 has been plaguing me for the past couple of months. And my husband is starting to hate her. Anyways... Two months ago the alternator completely failed on me on the middle of the interstate at midnight. Mechanic said there was a slow oil leak which slowly over time filled the alternator causing it to fail. Got the alternator replaced and the valve cover gaskets. We also replace the intake plenum gaskets and pcv valve for safe measures. Now I am receiving a slow up or shift down error that cause my car to turn off. My husband is an aircraft mechanic so hes pretty handed in cases like these. He ran the code reader and got a cylinder 6 and 8 misfire in the ignitor coils. We replaced those and all of the spark plugs. We are still getting those codes and the slow down/shift up error still happens. Although it hasn't cause my car to shut off but it drives really rough and seems as though it doesn't want to kick into the next gear.... Any ideas - I am not car literate at all. But any ideas would be greatly appreciated!

 

The valve body in the transmission was updated halfway through the 07 model year. From the sound of it, yours may be failing.

 

might try a TCM software upgrade to improve shifting

 

That issue is nothing to do with TCM.
Message means that and engine power is reduced so it cannot hold high gears because of misfires. So I think you need to measure compression in these cylinders since plugs and coils are replaced. But first I would check wires between coils and ECU.