Sea-foam goes like this.. 1/3 in tank, 1/3 in crankcase, 1/3 sucked into intake through vacuum line (very slowly).. Then change oil.. Did you get the 100k service done at dealer? if not did they use NGK plugs? If they are not NGKs get them OUTTA THERE NOW!!
If the CEL is blinking, you really shouldnt be driving it at all.. that means things will go boom