I second the fuel filter. When it sits over night or while you are at work, all the junk in the filter has a chance to fall back into the tank. After driving a bit the pump sucks it back up and the filter clogs again.
If it is independent of throttle then it is not the fuel. If it runs smooth with light throttle then bucks with more throttle it could be spark breaking down. Wet distributor cap is often the problem if it clears up with temp.
It bucks in all gears while appling throttle. If I rev it while out of gear than it spools up fine.
It did it this morning on the way to work. It usually doesn't do it then. However it was very light bucking. it feels as if there is no power at all then I fell a short (1/2 sec) burst of power than no power. Repeats a few times and goes away.
Check your PCV valve - I heard once that the engine block pressure vented into the poor seals of the distributor blowing moisture up into it - a poor PCV valve would do this. Also when it starts doing it just stop and pull the distributor cap off. Also check on the ignition connections to make sure you get good grounding to the distributor or else you could be misfiring the coils or not firing them at all when you loose power. Check for the smell of gas in the exhost too since that would indicate a failing spark - smell that all the time when I hear a car go by skipping a lot. Soot in the tail pipe would indicate a cat problem too. Spark plug gap too big can cause problems with high voltage wiring breaking down under less than ideal a/f mixtures.