I have an 08 FX2 with the 3V 5.4, 197k miles, and have recently developed a shudder/near stalling issue with my truck at lower (under 1000) rpm, but there are no engine codes. It typically only does it when I am gently accelerating or decelerating at low speed/rpm, say driving through a parking lot or neighborhood. I have also recently noticed a very strong gas/exhaust smell in my truck at start-up and cold idling. Has never done that before.
I connected a scanner that ZI borrowed from a friend that is able to monitor and show live data and I cannot seem to find anything amiss. Spark and all test good with the scanner. FRP is good, 39.7 psi.

A little history on the damn thing, in April of this year, I had that timing chain guides, chains, and phasers replaced after the chain guides broke. About a week after I had that done, the driver-side VCT basically grenaded due to what I later discovered to be chunks of the old guides being left in my damn oil pan (I found the chunks when I went to do motor mounts, don't ask). After all that crap was done, I developed a cylinder 5 misfire. Due to work demands, I didn't have time to mess with it so I took it to a local mechanic shop that had a decent reputation here in town. They diagnosed it as a loss of compression on cylinder 5, needs a new engine, to the tune of $11K. Yeah, no. I took it to another shop for a second opinion and it was just a bad coil on cylinder 5, compression was fine.

With my truck not showing and engine codes, I am really at a loss.

 

does fuel pressure drop during episode?

if not, and if you’ve ruled out basics, tune up stuff, it can get difficult.

but one thing that can cause troubles (including intermittent) and not throw a code is the crank sensor.

 

So I feel kinda special (aka stupid). I finally got some time to check things out more today and realized that I could feel the cylinder 5 coil/plug ticking with my finger tips while the truck was running. Couldn’t feel the same on any other cylinder. Removed the coil and went to break loose the spark plug to check things out and the damn thing wasn’t even tight, I could spin
it with my hand. Fml. Tightened things back down, took it for a test run through the neighbor hood with no more issues. Going to run it again in the AM when its cold to see if it does it again. Truck was at operating temp today.
I did discover that the last shop I took it to back in June, both stripped out the threaded hole for the coil AND cracked the tab that the threaded hole is in. So a new set of valve covers are in order.