john Podlewski

Haven't posted here in awhile but hoping someone has seen this issue?
I have a 05 FX4 5.4L 160K and the truck really stumbles at around 45-55mphs below 1300RPM's although it does do it at higher MPH's but always below 1300RPM's.
No Codes
It has done this for a 3 or 4 years now but seems to be getting worse. I have noticed it is only when there is a little acceleration (below 1300 RPM's)
Coasting at idle or above that RPM there is never any issue.
A few times I did notice the #5 spark plug was loose and I tighten that and it was better but that is not the case, as it is tight.
There are no DTC codes as I have an edge installed and even uninstalled it but still have the same issue. Hoping to find out what is causing this as the wife can no longer take the bucking almost like it's running out of gas?
Very annoying to say the least even the kids are starting to notice.
Could it be a coil or a fuel issue?
I did a tune up and new fuel filter about 50K ago.
But it did it before that too so that's not going to solve it, I don't think?
This is not a new problem just more often

Don't want to get raped at the dealer for a couple grand I don't have.
Lifted truck And a lot invested really want to keep it for a long time.
Hoping for some help

Thanks in advance really appreciate any avenue someone might point me in

John

techrep

iTrader: (1)

I would check the condition of your FPDM located under your spare tire normally corroded to the frame rail..

Rick's 06

You didn't mention changing your air filter. That's an easy one and if it's been 50K miles since you changed that it's overdue. I'd do the fuel filter again as well. I agree the FPDM is a good thing to check since that's a known issue.

tcp2

New spark plugs is the most common remedy.

powerranger262

I would say plugs, if you haven't done them yet. Throw a new fuel filter in it, check the fpdm, and clean the MAF and throttle body.
Do that easy stuff first. Then you get to dig deeper into things like the cats and injectors.

john Podlewski

Ok thanks
I'll check out the FDPM and Fuel filter is there a way to test them first though?
Hate to throw $$$ away
doubt its the plugs, as the issue was there before I swapped them out 50K ago and I do have a K&N Filter which I did 5K ago.
Truck starts great just below 1300RPM with gas applied is the problem
Everything I read about the FDPM says it wont start at all is that not true?

Thanks for the advice I'll keep you guys posted in the mean time let me know
Please....

powerranger262

K&n filter= clean your MAF and throttle body.

Hooah.soldier

No that is not true. Usually there are signs of it going out. They usually go out at 130-150k. You will be about to look at it and know it needs to be replaced. Order it from RockAuto.com , only $64 shipped.