Volvo: stalling, oxygen sensor, torque converter

Question
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Followup To
Question -
I have 240 DL.  Sometimes when I brake, my car will reve up and down and then stall.  I just had a relay put in as well as an oxygen sensor because it was stalling and not firing up.  It left me stranded a couple of times.  I just got the relay put in two days ago and it stalled again but was able to start it up quickly.
Answer -
Do you have an automatic transmission?  Does it stall every time you stop, or just some of the time?  Is the shifting smooth when you accelerate? Answer to your question.  Yes, no and no.

Answer
Because you said shifting is also not smooth when you accelerate, I believe you have a problem with the torque converter in your automatic transmission.  This device controls the connection between your engine and the geared transmission, and smooths all changes in gears.  The fact that you stall when you slow down means that it isn't properly disconnecting the transmission as you stop (just like pressing the clutch in if you had a manual transmission).  I would have that inspected ASAP.  Good luck!