So new member and new to the miata community. Picked up my 1999. Owner told me he believed it was an alternator which was my first mistake. So far I've replaced the battery, fuel pump and alternator. The car will run for about 4-5 mins and then dies. Electrical is still there, dash still on and radio still plays. Try to turn the car back on and wont turn over unless its jumped. What could be the problem?

 

Looks like a pretty popular topic on google, could be a lot of things, here's as start
https://forum.miata.net/vb/showthread.php?t=324212
https://forum.miata.net/vb/showthrea...ht=starts+dies
https://www.google.com/search?q=miat...hrome&ie=UTF-8