94 deville engine code

I pressed off and warm for 3 seconds on the heater control with key on
it gave me code 288 on the speedometer.
does anyone know what code 288 means? it has a 4.9 engine it is not the contour

Check this link, http://myweb.accessus.net/~090/dtcobd1.html#dia

none of the codes in the list are there
after holding off and warm for 3 seconds the only thing that showed was 288
there are no letters before it.

Why are you checking codes was the cel on,?

the CEL is on
when car first started it is off then within a few seconds comes on and stays on
the 02 sensor went on it recently and was changed and now engine has plenty of power and idles where before it was stalling at every stop and wouldn't go over 17MPH up a hill
the light has been on for some time now and i wanted to see if i could get it to turn off
the car also had a new fuel pump assembly and distributor installed as well as the coil, and wires.
it has a problem where when you first go to start it the starter barely moves and the lights go dim but if you try it a few times it will crank and start and sometimes it just cranks normally the 1st time
the starter was replaced about a year ago and the battery is brand new

i appreciate all of your help with this matter
the car needs to be junked but he can't afford to replace it yet

Have the battery load tested, check for corroded cable ends and grounds if all ok usually the starter is the issue.