I have a 96 astro with a vortec v6 and it started misfiring all of a sudden the other day-- by misfiring I mean at idle or under any load at all, if I give it a little throttle while idling in neutral it will smooth out and run fine but while driving or just idling it misfires and stumbles like crazy! The cel came on amd I checked the trouble codes and it gave me a #300 which is a genral engine misfire code. so I checked the coil and the cap and rotor and most of the basics but I have no clue what could be the problem. by the way, It has the EDI ignition... Any suggestions?

Low fuel pressure, bad plugs, wires are the usual suspects.