Hi i have a 2007 silverado 4.8l it has cold air intake deleted cats tuned by nelson performance also has after market muffler but not sure what it is it was on truck when i bought it. Anyway my question is what can be making truck run sluggish.i know there could be a million things just want any ideas where to start truck got plugs and wires done 20k ago at a napa also maybe i can start with fresh spark plugs n wires??

 

Has it always ran this way or is this something new?

 

Been a while i figured the tune would of heled but noticed no change