i totally agree, ive ran many led bulbs in the past, get an electronic flasher, got mine at autozone, big yellow one called "loud" problem solved
the factory flashers use electrical resistance to build up heat on the switch inside which turns it on and off as its heated and cooled, leds do not draw enough current to cause resistance in the flasher
and do not use resistors, unless you solder them in, they always come loose and you will get hyperflash or it will stop flashing, then suddenly work again