Ignition Coil and plug wire Inspection GM engines
A good GM ignition coil makes engine run smooth and no hesitation.
This is what the coil towers should look like.
A common reason for misfires, hesitation, and  
stumble is a corroded ignition coil and/or plug wire.
This example is from a 3.1 / 3.4 litre engine.

1- Burned / corroded coil tower
2- Burned / corroded plug wire

This can cause misfires under hard acceleration, or
 when cruising at a steady speed (45-65 mph) then  
accelerating to pass. Also will misfire at idle on wet,
 damp mornings. Causes a code p0300.
Corroded GM engine ignition coil and spark plug wire causes misfire code p0300
WARNING LIGHTS