I have a 1991 Comformaker furnace. Problem: it take much longer time (inducer) to turn pilot light "on". Then, flame come "on". But flame will not stay "on" when circulating fan is running. (The flame roll out in about I minute after the circulating fan is "on").

I also have a comfortmaker. I had this same issue a few months ago. There's a little rod (flame sensor) behind the first flame cylinder (from the left). I pulled that out (after first turning everything off) & sanded the corrosion off... put it back in... turned everything back on... presto. Problem solved.

If that doesn't fix the problem check the sticky at the top of the forum and sequence of operations.