Need some help I've got a 1998 Vectra SRI V6 with a misfire when on part load between 1-2000 revs in any gear. I've changed the plugs, HT leads and the spark pack was new 20k mls ago. I've even put redex in it to see if it clears but no success. Anyone had the same problem or got some ideas? ECU/Injectors/air flow sensor??????