I have an 05 F-150 Super Crew with the 5.4L.  I just installed a Summit/K&N intake system and PowerAid spacer on it.  What I was wondering is if on the spacer, is the PowerAid symbol suppose to be on the top or if the stamping for air flow on top?  The instructions didn't really tell and I know that they guys at Truckin just put one on a 08 Yukon.  The reason the I am asking is because I installed it and my mileage was 14.3 up from 14.0.  A few days later I towed a 25 foot toy hauler that was empty and my mileage went down to 9.7.  I understand that having a load will make it go down but it has been over 2 weeks and it is only back up to 12.2.  I do mostly freeway driving of about 20 miles a day.  I didn't think that it would take this long to recover so that is why I am wondering if I did something wrong when I installed the parts.  It only has 47,XXX miles on it and it also has an after market exhaust.  My dad suggest that I put on a computer to see if there is something wrong.  Should I put it on one or just wait it out?  Should I go a road trip and see if the mileage improves?  I don't know what I should do and I am hoping that someone out there can help.  Thanks for your time.  

The spacer shouldn't have a negative effect on milage. In fact it shouldn't do much of anything. Set your tire pressure to forty psi and see if your milage improves.  

ye also when i went to auto zone they told me that a spacer can improve the airflow to help with milage and i never even seen a diference yet i dont think that the spacer helps with anything