Need Help, Loss Of Mpg

[freeway2590]

Hello everybody, I need some serious help. I recently had 2 weeks off of work so I decided to do some maintenance on my 03 GMC Yukon 5.3l flex with 75000 miles on it. I changed my spark plugs using the newly gapped .040 ac delco spark plugs and autolite spark plug wires from advanced auto parts. I added a volant cold air intake and ram air scoop and changed my fuel filter. I also put 4 new skyjacker nitro 8000 shocks and changed my upper intermediate steering shaft. (just to mention, I have 285 75 r16 bf goodrich a/t tires on my truck) During the rest of my time off work, I only did city driving so I didnt notice the loss of mpg. But since going back to work doing freeway driving i've noticed the loss of mpg. In one full tank of gas, I use to get about 350 miles out of one tank. Now I only get roughly 300 miles out of one tank. I'm thinking about pulling out the spark plugs and gapping them to .060. I also ordered some MSD 8.5 mm spark plug wires, because I wasn't sure of the quality of the autolite wires. While installing the volant cold air intake, I did disconnect the battery and I also cleaned the MAF with MAF cleaner. I would just be happy if I could get my original mpg's back. Any tips or help from anybody would be gratelly appreciated.

 

 

 

[Silverado4x4]

Best thing to do is drive it for awhile, disconnecting the battery reset the computer and now the truck has to go through a relearn. You didnt have to disconnect the battery while putting on the CAI they just tell you that to cover there ass if the motor starts.