a P1131 mean that the O2 sensor on bank #1 is dying and you will need to replace it. I had this code a few weeks ago on my contour and the O2 sensor took care of it. Note it is the one by the firewall, the hard one to reach.
Also my fathers 95 had the similar code for OBD1 and replacing the O2 sensor fixed the CEL
they are about $65 from Autozone for new O2 sensors, replace it and you should be all set.
A hint to replace that sensor, since there is little working space, get the proper wrench and cut it down to a size were it will fit in the alotted space
