I have a 2003 Honda CRV.  The check engine light came on about a week
ago, and someone sugggested it might just be that the gas cap was
loose, so I tightened it and the light eventually went off.  Now its
back on again and the cap tightening didn't work.  In fact, it now does
a little jerk as I'm slowing to a stop, just before it stops -- it
almost feels like the engine is about to die, but it doesn't -- and
seems not to shift into a higher gear as readily as before (It also
seems like the idle speed is lower).  I won't be able to get it to the
dealer for a couple of days.  Any ideas on what this is and whether it
is safe to drive for another couple of days?

Thanks!