Not sure even if temperature has alot to do with it, but seems to choke on startup (can't catch, sputters,dies). Second crank is ok, sputters some, just catches, and takes a few seconds to get to idle.

Just replaced battery. No engine light (so rule out misfires on bad spark plugs)? Could it be bad fuel sensor? Fuel pump? Air filter? (air filter not sure how old, 1 year? 3 years max?). Have been using Regular gas for about 9 months, used to put in Plus all the time.

Rough starts have been happening probably past 2-4 months? Seems to be getting worse, but maybe because days are hotter? Seems worse when car has been sitting in the sun for a few hours.

 

I have an '05 S40 T5 and about 75% of the time when I first start mine in the morning it runs really rough, as if it's about to stall, for about three to five seconds and then all of a sudden, it runs perfectly and it does so for the remainder of the day. Sounds like a similar issue.

 

With the 2000-2004 years you are describing a failed fuel pressure regulator. Is it possible the newer 2004.5 + have the same issue? Anyone checked their fuel pressure?

 

the OP's issue sounds like the FPR and the second poster seems like it might be that the MAF sensor needs cleaning. both issues are addressed in the FAQ thread