Damnit, started to working and had a hard time getting all the fuel rail out. So left it in place, removed injectors, cleaned them and while reinstalling I damaged a gasket. Good luck I saw the small blue peace of rubber there.
Also changed the spark plugs on 2, 4 and 6 now but nothing obviously wrong.

 

Finished the work yesterday, did a short test drive and I think that it has improved quite a margin. But I will have to do more driving to find out. But I think I can really rule out any mechanical problem, with the new spark plugs it is now running very smooth at idle.
Will keep you updated once I had the time for some more test driving.

 

Oh, and I can hear a sliiiight "hissing" sound at the driver side (cyliner 1, 3, 5, 7). At first I thought there was fuel coming out or something but checked it immediately and couldn't see anything there. Thought it was the crank ventilation maybe? Is the valve located somewhere there? Does it give a slight hissing/humming sound?

 

Checked the PCV valve, I bet it has never been changed, or has been changed with an original part. It is functioning from what I see, but will replace it.
Hissing sound has becoming less I think, but it is hard to tell with the fan running, too...

 

Does your HEMI still have the original spark plug wires? Original wires cross back and forth over the top of the engine.
If so, I'd recommend replacing them with "shorties". https://www.summitracing.com/parts/t...1500/year/2004
One, it keeps the wires away from each other, less chance of cross firing. Two, it cleans up the top of the engine not having a rats nest of spark plug wires.
Three. I noticed smoother idling.
Something to think about, just throwing it out there.

Also, you haven't posted a picture yet.

 

Cheers and thanks, my car still has the original wires, I don't know if they have been replaced before according to the service plan, but will think about it.
So these "shorties" plug into the coil and the same cylinder the coil sits in?
​​​​​​Sounds interesting and not very expensive.


And here is a picture of the car after I fitted 285/70R17 on the stock 17" chrome clad steel wheels.

 

Yes, really makes the engine look cleaner.

If you have time and interest, I've posted a YouTube video of my truck a few months back showing everything that I've done to it for the most part.
It will show the plug wires and you'll see the fender flares, which look like it might help your truck.

 

Thanks for the video, those short wires are really looking clean and will make working a lot easier.

And to be honest, I removed the fender flares as I suspected there to be some rust underneath, which was obviously the case.
I like the look more without the flares, will think of painting them silver though and put them back on. But will have to think about it.

 

Cheers everyone,

today the problem came back, misfire on cylinder #7, but ONLY on petrol, NOT when on LPG.

It is very noticeable on a hot start, where it switched over to LPG after a few seconds. Runs very rough and the whole truck shakes, switching to LPG and it goes away immediatelly.
That leads me to the fuel injector wiring? When doing the spark plug change I switched the injectors 3 and 7 over. Now it is #7 again, so think it is the wiring.

Any other ideas? Am I missing something maybe?
Also ordered NGK ignition wires as mine are due to be changed, but that will just be an additional maintenance work...

Thank you!!

 

Wiring or PCM.