I just got a 90 z24 with the 3.1 in it and 5 speed 5 days ago. when i bought it i knew it ran like crap, and still does. I pulled the plugs and every plug has heavy carbon build up. chiltons suggested some senor or tunning is messed up. it will start right up but it feels like its misfiring while idle, when it warms up to about 200degrees it wants to stall but never does it keeps reving between 500-1000 rpms. and if i shut it off then restart it, it starts then revs to 2000 and idles down after a couple seconds. i unplugged the map sensor and it raised the idle and it seemed to run A LOT better for about 2 min then it realized the map was missing and started running like shit again. the plugs i took out where fairly new, no damage and still had the original shape just covered in black carbon. I think this means it running too rich and the air/fuel ratio is messed up. if anyone knows how to fix this or a possible solution it would be greatly appreciated. oh one more thing, the car was sitting for about year. not a daily drive but kept running.