Empire Wall Furnace Blower Problem
I doubt this is a motor problem. Sounds more like a thermostat problem, but not the main heater thermostat. The fan has its own control which, according to the manual, starts the fan 5 to 10 minutes after the furnace starts and then it runs until 5 to 10 minutes after the furnace stops. My hunch is that it is temperature-controlled and is cycling too fast at the beginning - i.e., it blows for 2 seconds, which cools down the initial air flow so fast that it turns itself off, then starts again after another 5 seconds, etc. until it runs continuously.
If it has always been this way, contact the manufacturer.
If it used to work correctly and recently started having this problem, a good cleaning may help.
By the way, I find it interesting that the blower kit is optional. 35,000 BTU is quite a bit of heat to generate without a blower. So I would definitely want that fan running well to circulate the heated air.