Nissan Repair: engine idle high after warm, mass air flow sensor, air flow sensor

Question
I have a 85 nissan 4x4 and it starts ok and will idle fine until it starts to warm up or until you start to drive it and then it idles about 2-3000 and wont come down even with feathering the accelerator. this high idle is causing it to overheat. Any ideas are appreciated. It has the 4 cylinder Z20 engine. Thanks

Answer
Hi Nate,

Two things come to mind. First, I believe it's a vacuum leak. You will need to inspect every inch of vacuum line. I know, it's a pain, but that's where I feel the problem is. The engine is revving high to try and compensate for the leak. Second, a bad sensor. This get's real complicated with this year of car. Without the ablity to scan the computer for codes to pinpoint the issue, you need to hit and miss, sorta. I feel that if it isn't a vacuum leak that it will be a bad MAF sensor. The Mass Air Flow sensor has a bunch of sensors integrated with it, barometric sensor, air flow sensor, altimeter, temp sensor. If you bought this from the dealer I would imagine it would cost over $500. I bought one on eBay for $15. Check those hoses and get back to me. This is about a 12 pack job, think?