I just received this car from a friend and so far everything runs great. It has a minor idling issue though. The car will idle around 800rpm's, but once I rev it up and stop it will bog down to 500rpm's for a few seconds then go back up to 800. I'm suspecting a vacuum leak somewhere, all the vacuum hoses are original so there are probably a few leaks here and there. I've replaced the battery, cap, rotor, spark plugs, plug wires, and air filter so far. I was told this was a common Nissan problem. Any suggestions fellow Z owners?

lots of little valves on the stock injection system, could take some time to track downt he culprit, sorry I can't offer any real help

Do you think running some injector cleaner would help? I'm going to run some of that later on when I fill up the gas tank. I also plan on seafoaming the engine later. Hopefully that helps... any other suggestions?