Your flasher is starting to crap out. That is always what happend to me befor it stops working all together or fuses its self together and just stays on. All it is is a piece of metal that bends side to side and after a while it gets weak and is easyer to bend so it goes faster. Replace the flasher and it will solve your problem. Also higher wattage bulbs can burn up stuff if your not carefull, I did that to my prelude tail lights and it was an expencive fix....