Volvo Repair: sputtering and stalling, volvo s80, throttle plate

Question
Hi, quick question please on Volvo S80 T6.  It doesn't happen all of the time but car will sputter and cut off.  It starts right back up but I am wondering is this an electrical problem?  They upgraded the throttle bottle system 3 months ago.  I cannot see a pattern of when it occurs only that the car just cuts off, when I seem to be slowing down.  Thank you for your time.  

Answer
The throttle adapts the opening of the throttle plate to maintain the idle (it doesn't have an idle valve).  When the throttle gets dirty the throttle opens the same amount (which it thinks is correct) but the dirt is closing it off some so it wants to dip low or stall.  It can adapt but it is slow to adapt.  SO, when you let go of the gas and start to stop it goes to the preset idle position and then adapts to maintain proper opening.  If its REAL dirty it can dip real low or possibly stall.  The solution is to clean the throttle blade and bore VERY thoroughly.  The T6 S80 is of course the most difficult car to do this on.  Our dealer sells a throttle cleaning and fuel injection cleaning which I think would take care of your problem so find your nearest service shop that could perform this procedure for you and inquire how much it is.

James