Just started thisso i replaced IGN. module and coil no improvement ...any ideas
It idles descent ,no check eng. light,coil wire is good,no smoke, plugs are good

 

Spark advance not working right or maybe a clogged fuel system, I recommend Chevron Fuel Injector Cleaner. I assume it is computer controlled, eventually it will throw a code and the check engine light will come on, then you can plug in a diagnostic tool and see what it is.

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Check the wires and if you have not in a while, replace fuel filter.

 

What year model car is this? L98 or LT1?