Intermittent ignition problem
 

My 2001 Accent has trouble starting every few days. When this happens -- the
engine cranks but does not start -- it takes several tries to get it going.
But once started, it gives me no trouble at all for a while. Between
episodes, it starts fine on the first try. What's problematic is that this
starting problem is intermittent, so I'm worried that if I just bring this
to a mechanic he'd have to make a guess and replace a few things.

It's not the battery or alternator (I had them tested at Autozone). It's
probably not the air filter, spark plugs, fuel filter or air filter: they
are all fairly new. Sometimes, I've seen erratic idling on cold start (RPMs
go up and down). Sometimes, the engine seems a little noisy on cold start,
but quiets down after about half a min. Any suggestions on how to approach
this? Thanks.

Chris