Two things. When you clean the MAF, it is imperative that you use an electronics cleaner so that there is no residue, or you defeat the purose of cleaning. Second, have you cleaned the IAC? Here is some info.
https://www.f150online.com/forums/19...ough-idle.html

 

Take the truck out for a spin at hiway speeds for about 15 miles. Bring it back where you can jack it up. Spin each wheel. Look for one or more that doesn't keep spinning. The brake system may need maintenance. Look for any exhaust leaks at the manifolds. Any leaks will cause the O2 sensors to read wrong. Make sure you are not running tires with too low of pressure. If the tires are not the original size, mileage will suffer via the different circumference. If not the original size, max out the tire pressure according to the info on the sidewall. Check to make sure you have no codes stored. If you have any, fix them.

 

it sounds to me like the truck needs the wheel bearings re packed, or there's a brake dragging (maybe the parking brake)


no reason to keep throwing money at something, is the truck throwing any codes?




what size tires does this truck have? what gears? do you drive it gently or you drive it like you stole it?

 

Buy from Uneek Supply in Bakersfield, Ca. I have done buisness with them and they were 1st class and carry the same coils that the low class people in FL. carry. And they are good coils.

 

The 1998 has COP. It is a nightmare to change the plugs.

 

I can't remember what the IAC is, so I'll have to go to the Library and look it up. I believe I have cleaned that, but I'll check it out.
The cleaner I used is strictly a cleaner, not a lubricating cleaner. Made sure.

 

The front brakes have less than 6,000 MI, and I am not having any issues with
them, at either end. Checked it out. No exhaust leaks either. The tires on it were not the original size when I bought it, but the mileage started dropping off before I replaced them, so I don't believe that is the problem. I tried running the tires at about 40# when I bought them, all it did was wear the centers out of the tread. No codes showing, had it checked on a OBD reader.

 

it takes like 45 minutes to change the plugs on a n/a 5.4

 

No dragging brakes, Tires are 265/75-16.5, stock gears, whatever size they are, I drive it like I have an egg under my foot on the accelerator pedal, and as far as I have been able to determine, the wheel bearings are sealed, and cannot be repacked.

 

looks like your tire size might be bigger then stock. That will make your calculations off. Seems to me like the stock size is 245/75 so it would only be a bit. Enough to throw it off a mile or 2 per gallon. Get a GPS and see if your speedo is slow.

 

The 5.4 had cops from day 1. It's the 4.6 that had coil packs till around 2000 or so.

 

Something wrong there. Can't remember if they ever used 16.5 wheels on an F-150 or not but they definitely didn't in '98. Looked it up and they only show 16in and 17in as optional. Can't imagine where they came up with wheels that would fit that truck in a 16.5 wheel. And I have never heard of wheel bearings that were sealed on an F-150 before the '04 new body 2WD on the front. Are you sure Johnny Cash didn't build this truck?

Maybe the 4X4 has sealed wheel bearings. I've never owned on so I don't know.

 

There was more than one factory size jethat, -at least two for sure. Mine are posted in my sig. It's always been lol. Yea , but it's a 4x4 off road/ tow package, - E4OD/4R100. Not sure what model the OP has ?

 

We had two 98's. One had 16's (chrome) and the other (4x4) = 17"s.

The truck w/16's was a 98 2wd reg cab/ short box w/4.2L.

Had an 01 for a little while, but iduno what it had on it ? They were black, if that helps

Maybe I'll it up after my second pot

 

OK, ONE LITTLE MISTAKE! The wheels are 16", steel/w slotted aluminum on the front. I have never gotten inside behind the hub, but according to the repair manuals I've read, the bearings are sealed units. I know all the suspen-
sion parts, tie-rods, etc., are sealed. I WISH I could grease them. Maybe that's just the 4wd model. I can't say. I didn't get maintenance records with the truck, so I don't know what the original owner did or didn't do.