2001 Pontiac Grand Am with 2.4 liter engine was brought in with the SES light on and a complaint of tip in acceleration problem and rough idle. The codes that were stored were P0105 for a MAP sensor malfunction, P0172 for a system rich fault and P0300 for a general misfire fault. I opened the hood for a visual inspection and heard an unusual hissing sound. I followed it to a vacuum hose that ran from the intake to the MAP sensor. Removed the damaged hose and replaced with a new piece and problem is now gone.
The above picture is of course the bad hose and it is just normal wear and tear that caused this. Below is a picture of the MAP (sensor three wire connector) at top right of picture and the new vacuum hose (the second hose down from the connector)
The P0105 was obviously caused by the MAP sensor hose, the P0172 system rich was also caused by the faulty hose because the computer thought that the engine was running under a heavier load and the P0300 was caused by the unneeded rich condition (particularly at low rpm). I was especially happy that this was a simple fix as it is my daughters car!