So I have an old furnace which started acting up. The heater would come on, gas, flames, and even the fan would turn on for about 60 secs. Then the flames would go out. I did all the troubleshooting and it told me to replace the intermittent pilot. The model I have is a S86e and I thought that's what I bought but it ended up being a S86a. The differences I see are that the vent damper is not jumpered and there is an extra TH-R wire input. Mine only has TH-W.

The gas turns on but no spark. Can I jumper the TH-R with TH-W?

If it has a thermocouple, change it.