Trouble codes P1131, P1151, P1237, and P0401 pulled of a 2000 Mercury Sable. What could be the main problem?

Seems the main problem is the P1237 code, the fuel pump secondary circuit fault. That indicates a problem with the fuel pump or a problem with the PCM fuel pump driver module. The fuel pump speed is controlled by a variable ground circuit which is supplied by the fuel pump driver module. A low fuel pressure problem can throw the other codes.