Why can't I get the check engine light to turn off n stay off

2001,Dakota just had to replace computer been idliling high most of the time light goes
on and off went to autozone they tested it said a sensor was bad changed it and that
made it worse. I unplugged the batterie n that worked for a little bit cleaned no matter
what I do it only works for a minute some times 1/2 a day but that's it the light comes
back on