Volvo Repair: 90-740 turbo wgn cold weather problems, cold weather problems, accelarator

Question
My 740 turbo wagon will run rough in cold weather.  When you press the accelarator it is as if the engine is choked.  You can ease it up to speed if the RPM's stay below 3000.   The problem will go away if the ignition is turned off then back on.   This can be done while in park or driving at any speed.   As said before it only seems to happen when it is cold, below 35-40 degrees.  Also warming up the car or cold start and go does not make a difference.

Thanks
Shawn

Answer
the only thing I have seen due similar to this is the knock sensor retarding the ignition timing but not based on temperature.I would check the ignition timing when it acts up.if this is ok I would check for diagnostic trouble codes in the fuel and ignition systems.