Volvo Repair: 240 -- running lean?, haynes manual, fuel mixture

Question
I have a '90 240 (B230).  The engine runs poorly.  I have had the throttle body cleaned, but this makes the problem worse.  It hesitates, surges, and often stalls when it is put in reverse.  Interestingly, when the outside temperature was -25C, the engine ran fine, but starting acting up when it got to -5C and is continuing now that it is warmer.  I checked the codes from the built in code reader.  There are 3 stored codes: 2-2-1, 2-3-1, 2-3-2, all indicating the engine is compensating for rich or lean fuel mixture (according to my Haynes manual -- but no further detail is given). Any ideas?

Answer
the codes really do not tell much.each sensor of the fuel system would need to be checked at the computer connection to determine which one is giving a false signal.unfortunately there are no easy nswers since there are any number of sensors that could cause this type problem.I would check for fuel leaking out the pressure regulator vacuum hose side.