My forced air unit fan comes on, then ignites and blower comes and runs fine. After 20-30 seconds blower goes off and fan still runs and after 30 seconds it re-ignites and runs then goes through same scenario

Have you checked the air filter for excess dirt?

Sounds like the burner is being shut off because of the furnace overheating. Check the filter. Also check for closed or blocked vents. If you have A/C on the furnace the coil could be dirty especially if the furnace has been run without a filter.