My 93 240 wagon runs great -- except in winter, in the first few minutes of running. Unless I rev up the rough-running engine immediately after starting, the car will die and not start again for 10 minutes or so. When it does start, one cylinder misses on occasion when cold. I replaced plugs and wires as a precaution (it was time anyway). The fuel pump is making some strange whining noises - could this be the problem? Once it's running -- no problem, and after it is warm, restarting is no problem. "CHECK ENGINE" codes are "mixture too rich" and "mixture too lean". Any suggestions are greatly appreciated! - Ryan