I also picked up a 90' NA last December. It was sitting for a few years in Florida so a lot of work has been done to it. I found a few in the junkyard so I have been able to get parts cheap. The guy that sold it to me is a Miata enthusiast so he did a lot of work before selling it. I had to replace the ecu, air flow sensor, air bag sensor, one radiator fan, hoses including a little rubber pljg on the left side of the engine that if it breaks It will ruin your day. Timing belt as well as gaskets along with woodruff key and short nose bolt have been replaced as well. A few other things that I can't remember. I spent ~$100 at the pull and pay and got all the replacement parts. Parts are cheap for this car. Mine now has 80k miles and love driving it in this weather. It is now my DD.
http://i1243.photobucket.com/albums/gg548/deexboy/2EE12BED-EE12-451E-9FF5-EBB2572AE315-1188-00000105FDD43AC6.jpg
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