hey my 1997 f150 2wd with a 5.4l triton motor has 267,xxx miles on it. the only things that ever needed replaced were the alternator and coil packs. i put an insys usa intake on it and true dual 2.5" glasspacks. it ran great for about a month and i got between 18 and 20 mpg. and now it seems less snappy and i get 14mpg no matter what. this truck is crazy reliable and the frame and body are spotless. i need help on getting my economy and power back so i dont have to sell it. thanks

 

Ever done the plugs on it? May want to do plugs if you haven't, and the seafoam treatment is very high up on my "recomend" list.

 

Have you tried to scan for codes?? sometimes there might be codes without the CEL

Have you cleaned the MAF sensor?
Have you checked for vacuum leaks?
Have you cleaned the throttle body?

 

I would take that intake off, clean the MAF, and see if that doesn't take care of it. Not sure what kind of filter your new intake uses, but oil based filters are known to cause problems with MAF contamination.

 

Plugs haven't been changed in a while only because they are a bear to change. MAF sensor is fine and the intake is spottless. My filter does not use oil. I was thinking more along the lines of plugged up cats but Idk.

 

I also gave it a bottle of injector cleaner which helped a little

 

Plugs helped mine a TON. Yes, they were a pain in the *** but it needed to be done.

 

yeah ill see about talking the old man into letting me do it again

 

Well, let me add some info here, mine had 259,*** miles on the originals.