get it scanned. see if your ecm is working properly...
heres what happened to me, surging and black smoke when I throttled pretty hard. mech said it was fuel related cuz of the black smoke. sooooo, new fuel pump, fuel filter, map sensor and o2 sensor. the problem remained, if not even worse. my mechanic called in a specialist who had a $7000 scanner, come to find out my ecm was telling the injectors to stay open longer than they should. $226 to replace. not a bad deal for a new computer. could have saved a bundle if i did that in the first place...