Pulled the EGR valve last night and it was surprisingly clean, considering how dirty the intake is (was). The truck wasn't setting any EGR codes so I think I'll reinstall the existing valve.

Still working on compression check for the last two cylinders and the O2 sensors. I think I recall reading somewhere that pulling the fender inner shields provides better access to the sensors. Either way, this rain every afternoon right when I get our of work isn't helping.

 

Problem solved -- replacing the two upstream oxygen sensors did the trick. Cleared all codes and none are showing as pending.

I'm going to leave the existing plugs in for a little while longer, since I didn't pull all of them to run the compression test and I'm working under a time/schedule crunch. I also decided to leave the old EGR valve in place. I'll give everything a re-look in about 10k miles (150k total vehicle miles)

The truck idles a lot smoother now, too. Not sure if that's due to the new sensors, the Seafoam liberally applied to the intake, or both.

Thanks to all who replied.

 

Glad you fixed the problem.

If the problem returns definitely do the compression test and see where you're at.

 

I had the P0300 on my 2008 Ram as well after the plugs being changed it was still tripping the P0300 and it ended up having something to do with the EGR valve being seized open. I am not sure if this will help you much but if the truck seems to have some power loss and the codes come back ill say check it next.

its was about 275$ for the one I got from the dealership but 4- 9mm bolts and unplug the wire harness and your set. very easy change,