I have a 2003 Dodge Ram 1500 5.7 Hemi 2x4.
About 2 weeks ago my truck devolved a hesitation from a dead stop almost like a studder when I 1st step on the gas. It usually only happens if I step on the gas with a moderate to a heavy foot and doesn't seem to happen if I am really easy on the pedal. I just replaced the gas cap as well as ALL the tubing (except for the boot on top closest to the rail that is in between to hard lines and goes to a 90* angle to the canister) on the charcoal canister and NVLD pump because of a P0441 code that popped up. I inspected all of the vacuum lines from the canister to the purge valve and everything looks to be in good working order.
I have no codes that have popped up or pending so I'm not sure where else to look. So any ideas would be great! TIA!!

I also recently replaced the plugs, wires, PCV valve, exhaust and intake springs.

 

Have you checked your fuel pressure? In neutral does the motor rev up quick if floored for a second? If you replaced your plugs recently did they show any signs of running lean?

 

The plugs where shot and had almost double the size gap. They also didn't show any signs of running to lean that I remember however I didn't take to much stock in looking at them because I had no compression on cyl#1. That is why I opened up the valve covers to look and discover a broken valve spring.
As far as it revving up quickly in neutral, The throttle response seems normal and quick.

 

So I now have a P0308 code popping up. So a misfire on the #8 cyl....
Plugs, wires and coil are all new. Compression test was good on the passenger side of the engine a month ago.
I'm really perplexed at this point unless something failed with the spring repair such as a valve not seating.
Any ideas?????

 

Ok so update.......
I also now have a P0300 code so now a random misfire on top of the P0308.
It seems to run just fine however the stutter from a dead stop idle concerns me.
The only other thing that I have noticed is that my gas milage has dropped 1-2 MPG.
Could it be the before cat O2 sensor???

 

I would recheck the compression on all cylinders. If o2 sensors act up i believe you can just unplug it to see if conditions improve. I think the computer runs off programed data with the 02 unplugged instead of modifying or self tuning itself.

 

So I unplugged the o2 sensor and reset the PCM by disconnecting the battery. I left the o2 sensor unplugged and reattached the battery.
The second that I started the truck it threw a p0032 code (which I expected because of the o2 sensor being disconnected) and took it for a ride. But it ran perfect with no hesitation or miss (not that it was missing before)during the drive.
So once I got home and the exhaust cooled down enough, I plugged back in the o2 sensor and took it out for another drive.
When I was almost home it threw a p0138 code (o2 sensor behind the cat) with no other codes present and it still ran perfect.

Since my compression check I probably only have 500 miles on it. All compression was 125ish on all but cylinder#1 which had 0psi which lead me to replacing the valve springs.

So I'm thinking that the o2 sensors are the culprit.

Unless someone else has any words of advice that might lead me down another path.

 

NTK or Denso sensors only. These trucks don't like the Bosch fellers.