All 20 year old furnaces need checked annually. They are at the end of their expected life span.
Yes, that's what I think I did. Set the fan at stat (auto), then rotated the dial just a bit. Fan came on. Ran immediately downstairs check airflow from register. Fan didn't stay on very long, long enough for me to see air streamers moving at same rate as before.
One more thing,
Good advice about checking these old furnaces. I'll have it checked out before the winter. Best to be safe and have it inspected. Thanks for all the good info fellas!