check engine light

What is your question?

My 1993 ESCORT has the "Check Engine" light come on. It will come on about 5 or 10 minutes into driving---stay on for about 10-15 minutes then go off for about 5-10 minutes, and then come on again. It will keep this routine for as long as I am driving. I changed my oxygen sensor about a year ago, so I don't think it is that. Is there anyone out there who tell me what might be causing this problem? I think that the catalytic converter needs to be changed. Did anyone else have this problem, and if so---what did you do to correct it? Thanks-MV