dcl on 1991 Lincoln Continental

I believe that "dcl" stands for direct computer link or something like that. Basically what it's telling you is that there is a bad or malfunctioning sensor. My advise would be to look for an auto parts store that does free code testing. I don't know where you live, but in Washington there's auto parts stores called Schuck's. They do free testing if you have one around your area.