[thstone]

Did you clear the codes after you replaced the MAF? If not, then the same codes indicating that the MAF is failing were still stored in the copmputer when the you took the car for a test drive (when the water pump failed).

As landrovered suggested, clear the codes using a scan tool or disconnecting the battery and then drive it and see if the codes come back. If so, post again here and someone will suggest the next steps.