I have a 1998 normally aspirated V70 wagon. 200k on the clock. Just started to run crappy. When cold it starts fine and the idle will raise and drop then possibly die. Once warmed for ~2minutes it will idle but the dithering idle will be less pronounced.
No codes shown, no light on the dash. I have checked and replaced the tube from air box to butterfly because it did have a crack in it. No help.

If I am on the expressway it runs good when under acceleration but if I lift the throttle it will basically die and drop below 1k rpms. If I feather the throttle it will just jump back to life.

If I am in city traffic I have to keep the idle up manually. if I drop below 2k then when I push the pedal the car will just cough sputter, give a little intake backfire and not go anywhere. then if I feather the throttle if will eventually just spark to life and take off again.

If I drive the car for more than 20 minutes or so then the problem goes almost completely away. if I make a 20 min trip, shut if off for a short while then restart problem is gone. This leads me to believe the problem is electrical and when enough heat sinks to the component it is fine. Problem only started happing when we dropped below 40ºF here in sunny texas.
I have seen these same basic syptoms on the net with not resolution posted. Any starting pointers from anyone? Have DVM and know how to use it.

Again...no codes shown and non show up when i hook to my code reader.
thanks,
Jason

 

Hello, Try unplugging the MAF while idling. If it clears up then you've found your problem. Are the plugs wet with fuel? Since it runs smoothly with more air (RPMs) maybe your fuel pressure regulator is shot. My vacuum gauge doubles as a fuel pressure gauge. Get one of them. Kira

 

problem ended up being corrosion on the MAF connector. Brass brush and some soda water cleaned it up...no more problem.