Dodge Ram 5.9 had p0305 - gone - now getting p0301

My son has 01 1500 Dodge 5.9 (gas) 4x4 automatic with 180k miles on it. Before purchasing the truck it had a p0305 - the dealer replaced plugs, wires, cap, rotor no more 0305. Tonight (days later) the CEL was on agian and this time p0301. I can rule out plugs and wires as these were replaced (wires are original style OEM installed by Dodge). I assume I can rule out the injector as it now moved from cyl 5 to cyl 1. I have no idea if the O2 sensors have ever been replaced, could it be going bad and causing the misfires on the odd cylinder bank?

Seems a valve problem would not change cylinders ( from 5 to 1) so its unlikely. Dirty injectors? I suppose a compression check is next, but my first (and worst) thought it is same cylinder bank, perhaps a cracked cyl head?

Other than a rough idle, it runs fine - no smells - leaks - etc.

Any help appreciated.

First thing I'd check would be compression and the fuel rail on that side of the engine! Coils as well used to go bad on those trucks. But if you just got it form the dealer I'd be getting it back there asap!

Those engines had alot of problems with dirt and debris in the fuel rails.

I took it back to the delaer this AM and they stood behind their word- they just called and said they had found the problem and were repalcing the fuel injectrors. I told them that's great but I dont want to be back there on Tuesday with another CEL.

They are covering the cost (300) for the injectors. I know for a Ford 300 for a set sounds about right, is that acurate for a Dodge?
Update - 3 injectors are being replaced. I asked for the fuel filter as well.

Thanks again for the help!

For a Ford V8 300 from the dealer! That's a good price! 3 injectors for that truck at the dealer should be about 300 bucks give or take!