Intermittent missfire

So, I have a 2000 Grand marquis. I bought it with
multiple missfires,  I changed all plugs and coils
and recovered all cylinders except #2. I will come
online and go away randomly. I can be cruising and
feel it come on and it'll run great, then just as fast
it'll drop out and the car starts stumbling all over
itself. Sometimes it'll smoke but most times it
dosent. I did notice though, while I have full power I
can hear a lifter clattering like crazy. When the
cylinder is dead there's no lifter noise. Bad or stuck
lifter? Anyone experience this?