Gas mileage? No.
Improved performance? Very marginally, nothing you'd really notice. The little HP you might gain with a CAI would only be at wide open throttle and that's hardly the place for good gas mileage. Your air intake is restricted by a throttle plate anyway.
CAI only begins to be of benefit when combined with other modifications. Your engine is like one big TUBE---just opening up one end a little bit doesn't matter...you'd have to work on the middle and the back as well to really get anywhere.
You might try synthetic oil--that could give you maybe 1 to 3 % better mileage; also don't warm the truck up on cold mornings...give it 30 seconds and just drive slowly until things warm up. Check tire pressure and put it to maximum allowed.
Also a tune up might help as would changing out your air filter if it's dirty. But all of these suggestions are very incremental at best.