Sounds like you've got the list down pat. I take it you've been hunting this problem for a good long while. As for the fuel filter, whenever I've had a bad one, it has always effected my RPMs at idle, not at high running. I would get a rough idle and stalling. But it's probably not the culprit if this is temp sensitive.

The other thing is whether or not these cars have an air intake temp sensor. If that's dirty or screwed up, it might give you bad reads at cold.

And yes, your car does have an EGR system. Well, I'm just taking an educated guess here, because FCP groton sells an EGR Temp sensor (expensive), valve (more expensive), and vacuum controller solenoid (really expensive). Pray it's not one of them.

I would recommend is finding a person who has an OBDII computer that can take snapshots of all your sensor readings when you're running (have any friends who are into tuner cars? they will have a friend who has a friend who has one). You take a snapshot of all the readings when it's running well, and when it's running badly. Put the numbers side-by side, and you'll see where the disparity lies.