My 02' supercrew has a 5.4 that gets 12.5mpg highway and doesn't have nearly the power of my 98' 5.4. I've installed flowmaster exhaust, K&N air intake system and used a superchip microtuner. Any help to these issues?

 

What type of fuel are you running with the tuner? and have you tried to reprogram.

 

I have tried all grades of fuel, 87, 89 & 91 octane. I started out stock with 12mpg on a trip from las vegas to denver CO. I then installed the exhaust and K & N. The last step was the supertuner. I also noticed that it has minimal power going through the mountain passes compared to my 98 F-150 or even my 2000 F-150 work truck.

 

If I'm not mistaken you need a min of 91 or 92 octane for the tuner. I would try to return the program to stock, fill up with high octane, run that tank out, refill, and reprogram with the performance tune.