Unless the car was in a major accident, I've almost never heard of the computer going bad on these cars. 157 is a MAF issue code. Try cleaning the MAF sensor and check to see if it has power going to it. Also, check your ground wires. To clear the other code -
[FONT=Times New Roman, Times, serif]To clear keep alive memory, disconnect and isolate negative battery cable for a minimum of five minutes. After clearing memory, it is necessary to drive vehicle a minimum of 10 miles to allow processor time to relearn value. http://www.troublecodes.net/ford/[/FONT]
I had the memory fail code as well, but I'd disconnect the battery because I had a short somewhere so it had a drain, pretty sure that's where I got mine.