If you have no experience on carburetors, you picked a heck of a one to start out with! The Hitachi carb, itself, isn't so bad, but, you likely have the VCM system (vacuum control module) on it as opposed to the more standard choke system, used on 1983 and earlier models. If you do, you will have a big, black, throttle actuator on the driver's side of the carb with an adjustment screw...which should never be adjusted unless you know what you are doing. The base idle screw is accessed from the driver's side and firewall side of the carb by turning the throttle drum. There is a good chance the base idle adjustment may not be your problem, rather, a problem with the VCM system (*Note: many refer to these as the "hopeless chokeless" system and end up replacing the factory carb with a Weber rather than try and figure out how it works and correct it). You should really get a Nissan factory service manual for your vehicle to help you figure out what is wrong and help you determine what you need to do to correct it. You could try Nico Club's site for a downloadable manual, but I'm not sure if they go back that far. There are currently about four or five for sale on Ebay for under $20 which is a deal considering all of the information it provides about your vehicle. That would be where I would start. Also, if the VCM filter is clogged, it will cause the engine to rev. This is a small, black plastic canister that is about the size of a pill bottle near the driver's side of the carb. There is a small, what appears to be a drain hole on the end of it; make sure the hole is located on the bottom side.