I have a 05 f150 w/4.6 107k mi. Regular scheduled maintenance throughout history and I am the original owner. Today while driving, my truck sputtered once when it warmed and stopped. I let it sit for a couple hours and started up just fine. This evening taking it out again it started again after it got warm, this time worse. At a stop light at idle it feels like it is about to die. When accelerating, there is little to no gitty-up at any speed... this only happens when engine is at Op Temp. Throughout any RPM (if any) there is no change in sputtering except then it starts bucking and shaking. She starts just fine when cold and no problems until warm

 

When was the last time the spark plugs and the fuel filter were changed?

Other possibilities: Corroded FPDM, clogged cats, sticky EGR valve.

 

I changed the spark plugs at 75k then fuel filter 15k ago.

If I let off the gas and coast from a speed, there isn't anything wrong that I can feel. It is under load and also at idle at a light that it has problems.

 

What brand plugs did you use?

 

It's been a few year since I did it... I don't remember

 

Changed out the FPDM and still a no go. Tomorrow I am going to check the fuel pressure and see what it's at.

 

If they weren't Motorcrafts, that may be your issue. Aftermarket plugs don't last.

The only way to check fuel pressure is with an OBD2 scanner, there's no test port.

 

I have a tuner that scans also... still no codes come up. If I put after market in it was most likely Bosch. I will most likely check fuel pressure and COPs tomorrow. Can I check the fuel pressure in line?

 

Bosch plugs are the biggest no-no in these engines. They actually come apart!

The FPDM controls fuel pressure, and it varies by design. You have to have a scanner that can read the PID. There's no way that COPs can be tested without some expensive bench equipment, resistance checks don't tell you if they are breaking down under load.

 

I think I am going to get one COP for it and switch it out throughout all cylinders until I find it. I have 1 definite mis-fire. What I've been doing is puting my truck in reverse or drive with the e-brake on to hold it. I will go through my receipts to find what I put in it.

 

FRP=39.75
IACDC=invalid
FPDC=.19
Spark=10.2 to 21
Longft1=1.02
Longft2=1.11

Not sure what the fuel pump duty cycle is suppose to be?! I read that max was to be .50

 

I'd pull the plugs and at least look at them first - I'm betting you probably have at least one that looks really nasty.

http://www.ebay.com/itm/VISTEON-60-1000-Ignition-Coil-Ignition-Coils-/330836213376?pt=Motors_Car_Truck_Parts_Accessories&hash=item4d075ffe80&vxp=mtr
OEM quality coils, cheaper and better than parts store coils.

 

Alright, update for the day.
In COP #7 there was either coolant or snow runnoff filling almost to the top of the plug. I blew out whatever it was and is now running better... for the time being. I am going to wait to find out if it either fills again or if it fixed the problem.