bad mpg, stumble at 40

[tdavid13]

Hi, I just bought my first expedition. It's an 06 with 122k. I noticed that I only get about 12mpg. My old suburban got 15-16. I put some injector cleaner in the gas with no changes. Is that normal? I also found out that right about 40 I get a stumble. If I let off the gas than it moves as normal, but it doesn't always happen.
No codes or lights on
I don't know about the plugs being changed but I heard they are a nightmare to change.
Any suggestions or places to look at or parts to replace?
Thanks

 

[Habbibie]

Do you know the history or the previous owner of this truck? That would be your most essential first step, without knowing that it'll get far more complicated to narrow down the best possible reason, but 12 mpg is the norm for these trucks, I average far less than that myself, others see 13-14 but seems the average here is 10.5-13.5mpg combined driving

 

[DanTheMan97]

Sounds like what mine did not to long after buying it. Mine was at about 130k. I eventually paid to get them replaced & that fixed the problem. I think I paid $400 to have it done, wish I would've spent the extra $50 to have the Ford dealership do it as I had the issue come back and after replacing several other parts I realized the shop never tightened one of the damn plugs. I'd recommend spending the extra few dollars if you end up having it done.

 

[08navigator]

Change the plugs. Buy the Lisle tool for when you break one. They suck. Mine was stumbling at 124k(2008) and plugs + fuel injector cleaner fixed it.

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[mquick5]

Sounds like what mine did not to long after buying it. Mine was at about 130k. I eventually paid to get them replaced & that fixed the problem. I think I paid $400 to have it done, wish I would've spent the extra $50 to have the Ford dealership do it as I had the issue come back and after replacing several other parts I realized the shop never tightened one of the damn plugs. I'd recommend spending the extra few dollars if you end up having it done.

$400 to change plugs?

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[DanTheMan97]

$400 to change plugs?

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Yes, $380 to be exact. Parts & Labor out the door.