Volvo Repair: V70 perfornance degraded, tacometer, proper heat

Question
Hi!  I have a 2001 V70.  When I am driving along at about 35 mph, the car sometimes runs roughly.  The Tacometer bounces around just a little bit.  And sometimes, I get the "performance degraded" error message.  Of course, by then, if I come to a stop, the car runs very roughly and I have to "reboot" it, or turn it off and back on again to get it to run smoothly again.
What's going on here? And is it going to cost me a ton of money.  I'm just out of warranty at 50,300 miles too.

Answer
It will downgrade the performance by retarding the timing, and if required reduce boost pressure.  It does this when it detects a misfire.  So check you plugs to see if they're fouled and the proper heat range for that car.  Look in the cylinders throught the spark plug hole with a flashlight and look for excessive carbon deposits.  Also if you run the car hard and are not using the proper octane fuel (owner's manual may say premium if its the T5 engine or high boost driving) this could also cause a misfire.  Upping to higher octane fuel or using an octane booster will reduce misfires even if you don't correct what is actually causing them.  If everything seems good and it is still doing it let the dealer look at it because the Engince control module may need a software reload (if the computer is compensating for a misfire when there is none, the electonics will ne to be checked).  If its a reload, it will probably be between 100-200.  All the other things should only cost you about 50 bucks or less to fix in your driveway.  Hope this helps.

James