99 ford explorer 4x4 sohc od light flashing but od works and no weird shifting

A flashing OD light is an indication of diagnostic trouble codes (DTC's) being set for the automatic transmission and related components. Even if you're not experiencing what you can tell to be problems, you should have testing performed to prevent something that is happening from escalating. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops