I have a 95 Grand with 204,000 miles. When it's first started, it smokes momentarily. When it's driven around, it doesn't smoke. But when it sits idling for a few minutes in heavy traffic, it will smoke for a bit. Anyone have any ideas on what I should tackle? It's a strong running motor though and is still pretty quick.

what color smoke?

I would run some NO SMOKE in it on your next oil change. My 94 did kinda the same thing when it was cold and if I would rev it up it would smoke (blue/black smoke) not bad just a little bit and not at idle speeds any other time, only when cold and I would rev the engine and this only happened when I would use LUCAS OIL STABILIZER, so I quit using it.

I believe the smoke is white/blue.

if the engine has good compression right accross, it could be the valve seals. If the engine runs perfect and idles nice, good compression, the rubber valve seals around the valve stems are rotted and letting oil down into the combustion chambers, burns up with the gas then smokes out the exhaust. You could remove a valve cover and take a closer look, sometimes you will find a pile of rubber/plastic laying beside the valve spring. If that is the case, the valve seals themselves are only a few bucks but there is quite a bit of labour if you take it some where. These seals can be changed without removing the heads, by screwing in a special adaptor into the spark plug hole on the cylinder your working on and hooking it up to your air compressor. This will force the piston down and both valves up and hold them in place while you use a special valve spring compressor to remove the spring, rotator and keepers, slip off the old oil seal and put the new one on, put it back together and move on to the next valve. Intake and exhaust valve seals are usually different sizes but look the same, don't mix them up. Some thing you can do yourself, should have at least a haynes manual for reference. The compressor does not have to be a big one, but should be able to reach around 120 pounds.

Thanks for the advice. I'm going to look into the valve seals first. I'll let you all know what I find out.