Hey I have s 1990 lumina 3.1 L Euro with a rough idle after the engine warms up. But when I pull the 60 amp fuse out from under the hood, it's for the blower motor/ only thing I noticed change after pulling and ain't labeled on the cover, the car runs perfect. Does anyone no why this would happen?
Anything on this would be appreciated, Thanks in advance

 

The blower motor could be pulling to much amperage causing a weak spark.