This has happened a couple times now but I dont know what could be causing it.

It only seems to happen when I'm at very low speed, almost idling, going through a drive-through at mcdonalds or something. Most recently when it happened I placed my order, and allowed the truck to move forward. Seems to happen when I almost come to a complete stop and then let off the brake to move forward without applying throttle, and that's when it goes into a sputtering fit. I threw it in Neutral so I could blip the throttle but it didn't help, engine sounded TERRIBLE, sputtering ticking shaking. If I threw the truck into Park it went away.

It's happened maybe 3 times over the last 3-6 months. So its not often, but its just really terrible sounding when it does happen. Same kind of scenarios every time: moving very slowly, truck starts acting up, throw it into park and it smooths out and goes away, doesnt happen again for weeks.

A little more background on the truck:
2006 F150 5.4L FX4
Bought it last june with 150k miles
Changed spark plugs about 4 months ago
Has an exhaust leak on the passenger side exhaust manifold
Seems to have the ticking sound when warm from the phasers, so they probably need replacing (hard to hear it over the exhaust leak though)
Brand new cam position sensors about 3 months ago (accessory drive belt broke, wrapped around fan, and took out the sensors, so had to replace them both).

A few thoughts on what would cause this?

Maybe phasers acting up?
Maybe a COP going bad?
Maybe some other sensor going bad?

Anyone have any ideas?

 

Possibly a fuel injector that is erratically staying open or closed . Try running some Seafoam thru the gas.

 

So this happened again quite a bit as I was waiting in line at the recycling center.

This time the truck was stalling.

it was fairly consistent. I'll be in gear at a stop (holding brakes), use the throttle to move forward about one car length, hit the brakes. At that point as I stop the engine starts to stall, sputter, etc. I throw it in park and it recovers and smooths out or it stalls. It did it again probably 4 times in a row as I worked my way up through the line.

Is there a diagnostic procedure for testing the coils (COPs)? Or a test for the injectors?

 

This happens all the time now once the truck is warm.

When the truck is still warming up, no issues.

Finally its gotten so bad I now have a CEL: code P0345, and a pending P0345 and P0300 (random misfire).

Read something somewhere about unplugging the cam position sensors, so I unplugged the drivers side CPS (bank 2, corresponding to the P0345). Problem is gone. Drove it all over town today, no issues. Truck even runs quieter. Obviously missing some power, but no other problems.

So does this confirm a phaser issue? Or does it confirm a VCT selenoid problem?

 

It sound a bit like my '97, 4.6 Scab was doing. Had total Cat failure at 232,000 miles. You may want a close look at your Cats. They seem to be the cause of a lot of problems.
Changed my Cats and O2's and had a new truck.
Good luck.

 

Well I've been driving it for a couple weeks with the drivers side cam position sensor unplugged, and although the CEL stays lit, truck runs great. Probably best its ran in a long time.

I'm thinking that confirms a phaser, CPS, or VCT selenoid issue.

So I'm going to do a total timing system overhaul (phasers, selenoids, timing chains, tensioners, guides). Truck has 150k on it anyway, I'm sure all the rest of that stuff could use a good refresh while I'm halfway down there anyway.

 

Problem solved. Not sure exactly what it is because I replaced almost everything (phasers, vct solenoids, tensioners, etc). Truck runs like brand new, runs so good now.

 

Have you checked the throttle positioner some times they need taken off and cleaned real well or just replaced I had the same problem on my 05 f150 I had

 

You may also check the throttle body itself. Something similar to this happend to me and i discovered that the throttle body was gummed up and just in need of a good cleaning.