poor performance

I have a 2001 silverado ext cab with the 4.8 and 3.42 rear end, I have an airaid filter kit and flowmaster dumps, everything else is stock, it has 52,000 miles on it. I did a basic tune up on it a few months ago (fuel filter, spark plugs,etc) I used bosch platinum plugs, but now it seems very sluggish off the line. The problem seemed to start after the tune up. Any suggestions please help!

Remove the Bosch plugs and put in some AC Delco plugs! GM designed the computer with certain parts and they work the best with those parts.