Been having some trouble lately. When the engine is cold, but parked, it runs fine. Once I start to move it hesitates, coughs and seems to be missing a cylinder or two. Two minutes later when the engine is up to normal temp., everything's fine. In fact, once it's warm, the engine seems to be running better than it has all summer - power is good (for a 3.0), fuel economy is normal (for a 3.0), no new noises or leaks. I've given everything the once-over and can't find anything wrong. The fact that it only happens when the engine is cold is what has me stumped. Anyone got any ideas?