Temporary Engine Stutter

I recently bought a 97 jeep and am having engine problems. After starting the jeep and driving for about 30 seconds, the engine seems to stutter and loses power. The rev's become erratic and this continues for a while before clearing, thereafter the engine then runs smoothly again.

Does anyone have any suggestions as to what this could be?

I've changed the spark plugs, oil, oil filter, air filter but no luck to far.

Thanks.

My wrangler did the same exact thing. Drove me nuts. Changed the fuel filter, plugs, wires, dist.cap, dist.rotor, and no change. Still would stutter. I ended up changing the Crankshaft Position Sensor, and it now runs like a champ again. Good luck.