Rough idle

[codename]

I have a 88 na z31. Easy start up, fires up will run good and idle fine for about 10 minutes. After the idle drops to 700 it misfires. Then misfire will come and go when it wants. All oem new plugs, wires, cap, fuel filter injectors and clean gas. No vaccum leaks. Can not figure this out. Any help?

[AzureblueZ]

When I was having a similar issue it turned out that my O2 sensor had gone bad.

[FrozenZ]

+1 on O2 sensor, also check and make sure that the O2 sensor harness hasn't flopped on a hot exhaust and partially melted

[bacon]

Just curious on this; I have the same issue, but don't get a O2 sensor code. Did you get a code for your bad O2 sensor?

[FrozenZ]

Pretty sure the ECU is only checking if you've got conductivity for your O2, not if it's actually working correctly.

[AzureblueZ]

Just curious on this; I have the same issue, but don't get a O2 sensor code. Did you get a code for your bad O2 sensor?

I did not get an O2 sensor code.

[badq45t]

Do not count on codes for these cars, not worthless but close. The O2 sensor and/or cylinder head temp sensor could fix it, I am on my 3x for both on my 84'