You're quite welcome. I never took notice whether my injectors clicked or not. I'm not sure what's up with the MAP sensor. Are you sure that you don't have a bad vacuum leak? I don't know a lot about newer vehicles. Only what I've picked up along the way. My '94 Safari is the only vehicle I've ever owned newer than '81. I've learned a lot from it in 10 yrs. Your best bet would be to go to GMC or Chevy non-specific & post a new thread with that question. There are a lot of pretty sharp people on this site. The only down side is you may have to sort through the info for the best advice. I haven't seen too many people being steered wrong here though. The alternative is to buy a Haines or Chilton manual on your vehicle, which you should probably do anyway. They're normally pretty good but don't always tell you everything you want to know. Thanks for the link. It'll come in handy.