Volvo Repair: engine runs rough, mouse nest, system temp

Question
I have a 1990 240.  I live in the bay area-when it drops below approx. 60 degrees Farenheit or above approx. 74 degrees farenheit my car will stall on start up.  If I keep the RPM at about 600 and let it warm up for about 15 secs it will not stall;  It will run rough for a 1/2 block but then surge and run fine.  On certain days I can feel a slight engine miss.  I changed the: spark plugs, cap, rotor and air filter 12 thousands miles ago.  I checked the plugs and other than a little carbon bulid-up they seemed fine. Also, the first 1/2 block is the roughest; I hit a dead spot in acceleration-it will run but no matter how much throttle I give it it will not go any faster.  The car will surge then take off. Thank you for your help.  Laura  

Answer
Hi Laura,
    Wow ...this sounds interesting....
   I'm at a loss as to why..."below 60 or above 74" could relate to any system..
   temp sender on cold start valve..maybe
    fuel press regulator...hmmmm
    bad gas...
    mouse nest....in your air filter housing.
    I sure hope it isn't one of the computers...
    if it is...get used....big savings.
  Bye,

  Bilbo