Gas Furnace on off quick repeat then starts

[Malcolm]

My AS 90+ gas furnace, when called for heat, starts the vent blower motor first, blower runs about 2 seconds, then shuts off, waits about a second, then starts blowing again for 2 seconds, then repeats. Sometimes it starts after a few times, sometimes it starts the first time correctly. I checked the air pipes, no obstructions. This time period is too short for the igition sequence to start, so I don't think related to that, or flame sensor. Pressure switch tubes seem tight and intact. Any ideas? Thanks.

[hvactech126]

Very possible a control logic in the board has failed.