It was replaced, do you think I should have it done again by LR?

 

You wasted your money on a new O2 sensor, 1:you need to replace O2's in pairs, so if you replace one front one then you need to replace both front ones.
2:90% of all O2 codes are because of bad plugs and wires.
O2's read exhaust temp and by the exhaust temp they know how rich or lean the engine is running, when it starts to run to rich because of a weak spark which in turn causes incomplete combustion of the gas/fuel mixture then the O2 reads the exhaust temp wrong and the ECU thinks the O2 is out of wack because the readings are wrong.
So a O2 code comes up, if you wait and continue to drive it without fixing the plugs and wires you will start to get mis fire codes, which means that the spark plug(s) are NOT sparking when they are supposed to and you are just dumping that raw fuel down the exhaust to the catalytic convertors, the cats then get really hot and will self destruct if left to go for to long.
So replace the other O2 and have a tune up done, thats new spark plugs and spark plug wires.
When your truck was running rough it was because of mis fires, a bad O2 will NOT cause a rough run situation, bad O2's cause really bad MPG.
The O2's cant do their job properly unless everything above them is doing its job well.
That means a good working MAF, clean air filter, good tune up and the proper gas.

 

As indicated above, it was replaced, do you think I should let LR have a look at it?

 

We posted at the same time, read my previous post to your question.

 

Spike555,
Let me get this straight. I need a good tune up to include new wires and plugs and I also need to replace the other front sensor? By the way, what do think about K&N replacement air filters?

 

Spike555,
Also, what type of wires and plugs would you suggest?

 

Yes you need to replace the other front sensor and you need a good tune up.
You did not need new O2's, but because you replaced one already you must replace the other.
If you dont then one side of the engine will run richer/leaner than the other.
DO NOT use a K&N air filter on a DII, if you do you WILL be buying a new MAF sensor.
The oil from the filter will contaminate your MAF and ruin it.
Besides that they are a waste of money, $70 for the filter, $15 for the oil to re-oil it every 10,000 miles, and you wont notice any MPG or horse power gains.

 

Magnecor plug wires and any spark plug that you want, if money is a issue then just use Champion spark plugs, if it is not a issue then use Iridium spark plugs.
But DO NOT scrimp on the plug wires, you can throw in cheap plugs for right now and replace them yourself later, the plug wires are a huge PIA and you do not want to be doing it again in a month.

 

What brand of Iridium plugs would you use? Money not being a factor?

 

Denso or NGK, I used Denso when I first did my tune up, I know have E3 spark plugs in my Disco.
www.e3sparkplugs.com
I bought them from JCWhitney, not saying that you should use them, but that is what I have in my truck.
Whatever you do, make sure that you cross reference the spark plugs that you want with the part number on the manufactures web site.
JCWhitney sent me the wrong plugs and my truck ran like crap.
Also I have a coupon code for free shipping from JCWhitney, so if you want it let me know.
They also sell Iridium plugs.