could be related to the fuel pump or fuel filter I suppose, but could also be spark related - I've heard an ignitor/ignition module that's going out can cause misfiring before totally crapping out, or maybe your ignition timing is just way off :dunno:

If it pulls fine at high rpms, no missing or cutting-out, than I doubt it's fuel related, and you've already covered the relatively cheap stuff on the spark side.

Is it like that at idle or only when you're trying to accelerate from a stop/slow speed?