My problem was similar, except it would get worse with drive time, instead of better like yours. I replaced all 8 of my coils with new ones and it went away.

It almost sounds as though it could have an intake gasket bad, or something similar causing a vacuum leak. After the car heats up and everything expands, it runs fine. When it's cold and running rough, spray some water from a squirt bottle (or something like that) around where the intake bolts to the heads, and see if that makes it run smoother for a couple seconds. Don't soak it with a hose, you dont need to flood it with water.

Just a thought.

 

i have a similar problem, mine bucks real bad under 1500 at low speeds and the power and economy absolutely suck....but the crappy shops around here can't figure it out [:@]

 

ummm... you can't use water to find a vac leak, you need something that's combustible

 

Oops, your right.

I've used throttle body cleaner or WD40. I was thinking of the old water on the header pipe, to find a missfire.

Sorry.