soon as u start up clouds of smoke
blue smoke from exhaust lots of.miss fire as well on 1998 BMW 540i
sounds like you need diag and est as what is wrong and how much to repair could be several things
Sounds like valve seals. Engine oil in the top of the head will drain down the valve stem through a worn valve seal when the engine is off. Once you start the engine the oil in the combustion chamber will burn casuing smoke. This is not a cheap repair but you might try an oil conditioner product.
this may be a oil superater under the intakemanifold also oil tube be sure and check it too.i have a 540i thats what it was.the miss is oil fauling your plugs.dirtcar in ar.phone#501-745-7564