This is for my mom's 850 turbo wagon. She drives about 45 min to work everyday and up until recently it hasn't had any problems. But as it has been getting colder out, some problems have started to arise. It starts fine, but you can hear that it isn't running to its fullest potential. After about 15 min or so it kicks in and starts to run normally again. This has happened about a half a dozen times and a couple times it has died after being on for 2 min. Any suggestions as to what is happening?

 

Ok a couple questions...

1. What year is the 855?
2. Any check engine light?
3. When was the last time a stage 0 was done?
4. Have you tried a bottle of dry gas? ( you may have some moisture in the tank from the change in temps)
5. is it sputtering at idle or under a load?

 

One more question.

"you can hear that it isn't running to its fullest potential"

Can you put that in terms a little easier to understand. Is it not idling at a fast enough speed, does it sound like it isn't firing on all cylinders, it's having a rough idle ..... I have no idea what it's fullest potential means

If it's sputtering that kind of sounds like an ignition problem and if it clears up once it's warm and runs well going down the freeway it might be the ignition wires are starting to fail when they have some frost/moisure on them and might be arching to ground.

As in the post above you might want to pull the distributor cap off and take a look for moisture, dirt and or carbon tracking. If the contacts in the cap and on the rotor look pretty burned it might be time to replace them. If you can't remember when it was last done, again it's time to replace them.
How old are the plugs. Have you checked a couple to see what condition they are in?
Do the ignition wires look ok? Any visible signs of cracking?

The engine is kept idling by the idle air control motor (IAC). It might be that yours is wearing out and can't adjust fast enough to changes as the motor warms up. It is usually constantly adjusting to maintain a fixed rpm point. When cold that point is higher and as it warms up that point lowers. If you turn on the AC or the defroster or put it in gear you notice it drops some RPMs for a second and then returns to where it was, this is the IAC adjusting for the added load. Same thing in reverse when you take it out of gear or the AC turns off. The IAC motor can be removed and cleaned with a Q-tip and some carb cleaner. It's best to hold the IAC with it's motor up when you spray into it. Less chance the spray gets into the motor.

 

Sorry for the late reply, but since it has gotten warmer out there hasn't been any problems, so I am going to assume that maybe it was just bad gas or just water blockage. It may just be attributed to the coldness, but I appreciate both of your responses and if this happens again, I will definitely refer back to this.