I think you have a 1995 because of the 157 error code. (Not a listed code for 96+ cars.) Before replacing the MAF you might try cleaning the tiny sensor wires within the sample tube. Use a spray electronics cleaner available at radio shack of some auto stores. Clean the electrical connector as well and reseat the connection. There is a wiring harness recall for the older contours, so you may want to check if you have any cracked insulation on the wires to see if you need the engine wiring harness replaced. If your under 100K miles, I believe the dealer will do it for free.
Not sure why you don't see a CEL until the car is moving?
