Irratic Idle

[91GTS]

My 91 GT-S will speed up and slow down at idle, between ~200 rpm and ~1000 rpm. This seems to happen when it gets warmed up. It pulls fine, with no missing. Sometimes it will die at a stop. This car had sat for about a year. Any ideas? Can this be computer diagnosed? Thanks.

[Pineapple]

Its the idle control valve. Reset idle and timing. Remove battery -ve terminal for a minute to reset ECU may help. Also try clean TB before all of the above action.

[91GTS]

thanks. The throttle body looked pretty dirty.

[Pineapple]

Then remove the hose one at a time and spray throttle body cleaner through the hole into the TB. For sure you'll need to remove -ve from battery and reset idle + timing after cleaning.

[Blane]

Mine does the samething but doesn't the engine doesn't die.