Land Rover Forum - 1998 Discovery Code: p1314 Running Rough, already replaced several things

Hey guys,
1998 Disco LSE 4.0L
I've had a number of issues, and have already replaced a bunch of stuff, but now I'm pretty much at a loss.
Currently it's throwing a p1314 code (Misfire likely to damage catalyst). It's running rough, but not always. It usually will run fine when started, but after driving for a little bit it will run rough, lose power, etc.

Here's the history of the issue:
2011- Bought it, it had a check engine light on, but nothing seemed to be affected.
2012- Checked the code- It was a P1193 or P1191, (don't remember which) Oxygen Sensor Heater Circuit Open downstream (At the time, had no idea what that was referring to so I left it. (Smart right?))

Last year 2014, started getting worse MPG,
June, I'm driving in the mountains, and I feel a slight stutter and loss of power, but didn't feel it again till;
July, Car wash: washing the engine compartment because it was covered in mud, then it wont start. A few hours later, get it to start, but running extremely rough and backfiring. After a couple of minutes, the Drivers side cat was red hot (fuel wasn't igniting till it was in the cat.) Not drive-able. Cylinder 1 wasn't firing.
Since then, I've replaced:
Coils, Plugs, Wires, Drivers side Cat, o2 sensor, (and the alternator; it wasn't putting out enough voltage; probably unrelated.)
Before I replaced the cat and the o2 sensor, I checked to see if coil 1 was giving spark to cylinder 1; it wasn't.
Going to test the new coil I'll let you know what I find out.
After I replaced each one of those things, it would run ok for a day or two, then go back to running poorly.
After I replaced the Cat and O2 sensor it ran great, with plenty of power, but a few days later, it started running poorly again, which is where I'm at now.

Could it be a control module issue? another sensor issue?