My truck has been running like ****, sputtering, rough idle no power at times and all that good stuff. I was going to finally scrap it and replace it until I found out that our new bundle of joy is going to steal that budget on arrival. (it's a girl, so I suppose I should get used to that) I went to take the truck for a drive the other day and found that I had left the key in the ignition over night and drained the battery. No biggie, toss it on the charger for 24+ hours and try again. Well, my cel is gone and after an hour long drive not only did it not come back, but the truck has never run better ! So of course I'm in love all over again.
So how can I go from a pile of left bank misfire codes to running like a british watch?

 

Flaky ground connection somewhere rusted back shut? haha

Start simple, check plugs, wires, all the engine bay ground points are clean and tight, wire loom that runs along top of firewall - peel open the plastic protector and look for rubbed through wires (sand/dirt etc in there will wear through the wires rubber shielding), popped fuses, connections that effect fuel/spark ie. mass air, o2's, temp sensors... check filter, check for vacum leaks from air ftiler box back to throttle, then connections on back of throttlebody, check for sticky/dirty throttleblades and idle bypass motor thingy, run her dry and put fresh gas in with seafoam or other cleaner for a few tanks...belt condition, oil level/condition etc.

 

I would hold off celebrations for a while. You cleared codes with dead battery. But many codes have to happen on two drive cycles (some evap codes take four repeated cycles) before they turn the CEL on again. So it may pop back up. Stop by a parts store and let them read codes for free, and write down the numbers, don't buy any parts. Post back here.

As for the female offspring - college fund...

 

I have an ultraguage but the codes have cleared. Other than the typical 3 amigos related I was getting 0300, 0301,0303,0305 & 0307. All left bank misfires, but between myself and a non land rover mechanic we could not find a cause for it.
I replaced the plugs & wires 6 months ago. I can't tell you the brand, but it was what my indy rover mech insisted that I use.
If it's any help: the problem started shortly after moved from the desert to the rainforests of Connecticut.
Also, I cleared the codes last week, disconnected the battery and connected the battery terminals. The problems reappeared almost immediately.
Could it be possible that the battery was just weak enough to create an issue? It sounds silly, but I've also read about the wrong bulb in a directional wreaking havoc with these things...

 

Check the coils, maybe they are loose, shaky, water leaking on them from somewhere, something rubbing the wires where they connect there?