Sorry I have been so quiet on the truck forums as of late. But on to the issue...

My truck, '04 F150 5.4L 4x4 was left in the driveway a bit too long as I was driving the Saturn for the gas mileage. Well now we need both vehicles, and I got the battery charged back up, oil changed and a fresh tank of gas in it, and am finding that the truck tends to stall once warmed up at low speed such as when approaching a stop sign, or manuvering in a parking lot. I ran a tank through, and filled up adding a quart of Seafoam to the fresh tank. (the pint bottle says treats up to 20 gallons so I figured the 24 ish gallons deserve a quart...).

Anyway since getting it back on the road, I have noticed that once warmed up, the idle is around 350 to 400 rpm...

I am getting no codes.

I have reset the program to stock but the idle remains low.

What else can I be looking at to fix this? I can guarantee that my lovely bride is none too fond of this behavior!

For what it's worth, I am planning on keeping this truck for a good long time... It's paid for!

 

Sounds like the classic dirty throttle body issue. The dropping of the RPMs to the point of stalling are the symptoms I had until I finally cleaned the TB.
Here is a good How To to bench clean the TB:
Bench Clean TB

Before removing the TB, clean it in place. Remove the air cleaner housing and using a clean, lintless rag soaked with WD-40, wipe out the inside of the TB and butterfly valve. It is completely gummed up in there, I suggest removing and cleaning the TB as per the link above.

To clean the mass air flow sensor, try this:
Clean MAF

and finally, I would swap the fuel filter if it wasn't replaced recently.

Good luck!

 

StoveTop, Thanks for the links... You verified my suspicions...

BTW, love that truck. Just about the perfect stance there...

 

Okay, worked late this evening, swung by Advance Auto on the way through, grabbed some B12 Chemtool and some MAF Cleaner. I wasn't confident the B12 was MAF safe... I had a little bit of fun tearing the air box down, and honestly the throttle body didn't "look" gunked up, but I shot the snot out of it with the B12, and cleaned up the MAF then reassembled the whole shebang. Now the K&N has about 15K on it since the last cleaning, so it is getting a useful cake, but isn't jammed... Now having reassembled the whole thing, and road tested it, admittedly somewhat briefly, no more stalling, and 650 rpm idle that is smooth...

Go figure...

Tomorrow morning will be the real test, but so far it looks good... I figure once I get it running right with a stock tune, I can take the tuner to it, and tweak some to get my MPG back...

 

Just FWIW, drove the truck in to work again this morning. Ran smooth as silk, no stalling, no rough idle non of that junk... Thanks folks!

FWIW, I still need to do the filters, I am honestly dreading the fuel filter. One thing I have never liked about Fords is the fuel filter arrangement... But it is what it is...

 

Ah K&N, I bet that's the source of your problems. Those oiled filters can gum up the TB and fubar the MAF. I would consider going back to a paper filter until you replace the K&N. I replaced mine with an AEM filter which is cleanable and reusable like the K&N, but is a dry filter...does not use oil.

 

hopefully you removed the tb from the intake....

 

Gotta ask, why would that matter? The Haynes guide and the Chemtool can both said to clean it on the truck...