Loping/rolling engine start?

'97 Sport, 4.0, AW4, NP231.

Lately I've noticed when I start the engine after it has been sitting over night, especially when it is cold out (< 30 degrees), I get kind of a 'rolling' or lightly loping start. It always fires right up easily, on the first try, with no problem. But as soon as it catches, it has a moment of loping or rolling where it feels like it is gaining momentum and speed and then smooths out. I've currently got 5w-30 in it, so I don't believe it is the effect of too-thick oil.

Any idea what might cause this, or what to look for?

Assuming there is no check engine light?

When was the last time that the spark plugs, distributor cap, rotor, plug wires were changed? Gotta eliminate tuneup stuff before moving onto more complex possibilities.

You could put a fuel pressure gauge on the schrader valve on the fuel rail when starting and watch it closely to see how your fuel pressure performs. It's not impossible that the pump may be starting to weaken.

Does it only do this up to the first shift, and feels fine idling but then bogs down when you try to accelerate, but works great after it's shifted for the first time? I'd bet on a bad TPS.

No check engine light.

I bought it less than a year ago and didn't perform a tune-up; however I did go through the ignition system and everything looked good (the PO took very good care).

It doesn't do this at all while driving - no bogging or anything like that.

Idling is usually just fine - every now and then it gets a little lopey/stumbly when idling but it's pretty rare and usually goes away immediately.

I ran a bottle of Techron through it recently as well, and because it's temperature-dependent I don't suspect injector issues....

I suppose as a matter of course, I could replace the rotor/cap/wires/plugs.....

Well, at that cold of a temp the fuel could be too cold? When I was living up in WA state, I ran some of that liquid "de-icer" crap or whatever you call it in the tank, and never had an issue.