GM-GMC: 2003 Chevy Silverado 2500 HD Check Engine Light, chevy silverado 2500 hd, chevy silverado

Question
I have a 2003 Chevy Silverado 2500 HD with 6.0L gas engine. I just changed the spark plugs and wires. Why does my check engine light now blink when I go above 60 mph whether or not I use the cruise control?

Answer
Generally if the check engine light is flashing it is a very very bad thing.  It is an indication that something is not right and could do damage to the engine.  In most cases it is a missfire or a completely dead cylinder.  Double check the wires and plugs you just replaced.  Or if you have access to a scanner you can display what cylinder is having trouble and focus your attention there.  I would not recommend driving it until you have found the problem.
Hope this helps