Significant Drop in MPG need help!

[Minero]

So I recently did a bit of work to my 1998 XLT 4x4 5.4L. Here's whats new: New oil change and filter, did two rounds of Chevron Super Concentrated Fuel Treatment, New aftermarket intake and filter, weather has gotten much colder around here (I've noticed I have to hold the ignition longer to turn the car on early in the morning). Anyways I was usually avg 10-12, now I'm around 8! Thinking I need a tune-up, gonna go and check the tire pressure later today. Anybody with any ideas, it would be greatly appreciated!!!

This is a pic of the new intake and filter:

 

[superexpy]

Im thinking its the weight of the dirt on your motor is effecting you MPG
Try dis-connecting your battery for a few minutes. Your computer may not recognize the changes you made. A couple of other things id look at is you fuel filter and plugs. One more thing to try is change out your DPFE sensor. I changed this for fun a couple months back and picked up 2MPG

 

[tonydiv]

Have you checked to see if you have any vacuum leaks? (especially the elbow on the back of the throttle body)

Is that an oiled filter? Those can mess up the mass air sensor.

A decent scan tool will let you look at the various sensor outputs, which can give you an idea of what is going on.

 

[Minero]

Im thinking its the weight of the dirt on your motor is effecting you MPG
Try dis-connecting your battery for a few minutes. Your computer may not recognize the changes you made. A couple of other things id look at is you fuel filter and plugs. One more thing to try is change out your DPFE sensor. I changed this for fun a couple months back and picked up 2MPG

haha yeah its pretty embarassing, any suggestions for cleaning up the engine? I only recently started working on my expedition. but anyway, yeah I've disconnected the battery per instructions that came with the intake. left it disconnected while I installed the audio, altogether it was disconnected about 3 hours give or take. Gonna get a tune up soon. Considered doing it myself but tooke one look at the tight space and got scared I checked the tire pressure and noticed I'm kind of low on all four tires. but idont know if that would change my mpg that much.

 

[Minero]

Have you checked to see if you have any vacuum leaks? (especially the elbow on the back of the throttle body)

Is that an oiled filter? Those can mess up the mass air sensor.

A decent scan tool will let you look at the various sensor outputs, which can give you an idea of what is going on.

No leaks as far as I know, I actually just replaced that elbow behind the intake manifold. Had a rough idle and found out that was a common problem. That how (I found this site to begin with!)

Also i'm not really sure if its an oiled filter. I don't remember, any way to find out after the fact?

 

[Milwaukee]

You not only one.

I lost 2 mpg this month. Wasn't too happy. Used to see 16-17 in city.

Right I'm lucky to get 14-15 that it.

What I notice that it get forever to warm up 190oF I was thinking of remove fan clutch and put electric fan in there.

 

[superexpy]

You not only one.

I lost 2 mpg this month. Wasn't too happy. Used to see 16-17 in city.

Right I'm lucky to get 14-15 that it.

What I notice that it get forever to warm up 190oF I was thinking of remove fan clutch and put electric fan in there.

I have been running E fans for 8 years now on mine. I bought two fans off ebay for 30$ per and bought a thermostat controller from napa for 8$ and wired it all in. Took me about and hour and have never had a problem