I have a (new to me that I bought):

2000 Land Rover Discovery II.

It starts, idles fairly smooth around 700 rpm, shifts in reverse and drive. It has normal acceleration power in park or neutral. When I drive it, it accelerates to around 30 mph, but not much more so no top end power.

1. Has exhaust off from catalytic converters
2. One Key which is electronic and cover to chip missing. It starts the vehicle.
3. The Key does not match the driver door key lock (this entire driver door latch looks replaced).
4. Lights come on dash only when start. None stay on.
5. The security red light never comes on. Beeps
6. When I have vehicle idling and press the door lock button on dash, it shuts off.
7. I have to manually unlock each door (but locks doors but does not unlock doors)
8. No lights on when driving.

Do you think vehicle is in LIMP mode if knowing it starts, drives up to 30mph?

I cannot try re-setting because drive door handle key does not match. How will I ever be able to fix this?

Other knowns: Driver Side Power Window regulator and motor out of door. Power steering pump is bad and leaking. Any help is much appreciated.

 

Are you sure the t-case isn't in low range? You don't mention checking this but that is the very first thought I had.

Looking through your list, here are the things that stand out to me in order of the concern they cause me. (I am not a guru)

6. Restate: When you press the dash button to lock the vehicle, the engine dies. If this statement is accurate it is quite concerning to me. At best it means the BCU is telling the ECU to kill the engine which would mean the vehicle is kinda immobilized. At worst it means you have a serious short in your electrical system. If it is the latter, then you can cause yourself some real grief and money fast if you don't correct it. Validate that all fuse locations have the correct fuse installed. All too often someone fixes a short with a bigger fuse that makes the wiring harness the fuse.

5. Flashing red light suggests to me that the immobilizer is doing something. The fact the car starts suggests that either it is not doing it well or that it is partially by-passed.

First thing I would want is a nanocom connected to validate the status of the BCU, ECU and immobilizer. It sounds like you got someones project and among their shenanigans was an attempt to bypass the immobilizer and that they didn't finish the job.

If that is beyond your reach and you wanna try the door EKA code first, remove the drivers door handle. From here you have some options. Take it to a locksmith and have a key made for the door lock, or take the key you have the works in the ignition and have the door re-wafered to that key. Or learn to re-wafer it yourself. It's been a few years since I was working on this area, but IIRC once you have the handle out you could just put a screwdriver in the electric switch that is behind the lock and enter an EKA code without they key. Also, you could just remove all the wafers (for now) and then any key would turn the lock.

In other news, either I have given you good advice, or it's crap. If it's crap then I have invoked Cunningham's law and someone will be along shortly to tell us I am wrong. Either way, good luck!

 

It is in High. There is NO red alarm light ever blinking. I am on same page with you since driver’s door handle and key lock does not match others and the ignition key won’t even go in it. The door lock is gloss black compared to flat black on rest. I don’t even see any wiring come from door handle. The window regulator and power window motor is out of door.

I am on same page with you with BCU/ECU. With the engine running and you press dash door lock, it LOCKS it and shuts engine down. Engine restarts upon turning key again. BUT button never unlocks doors and I have to manually unlock them by opening each door from inside vehicle. I will check fuses. The radio is out and I can tell the inner dash has been removed.

Upon driving yesterday, it went through all gears and drives fine. But I can’t even find how to get driver door lock off. It’s way up behind door metal.

 

Just wana chip in on the unlock button killing the engine. My truck has done this since i bought it around 5 years ago.
I got motivated for a bit one weekend and replaced the BCU. ECU. And fuse block 1 at a time. None fixed the issue.
Also dug allover for shorted wiring. Gotta be there somewhere.
Otherwise the truck drives perfect.

I have a nanocom as well and have gone over everything possible 10x. Ive just set the doors to not auto lock. Far from ideal. But easier at school pickup for now.

 

Thank you for the input. I think I am going a different route now by using the 2000 Disco 2 as a parts truck for the 2001 Disco 2 I have (it just has a bad transfer case) or I will sell the 2000 and just focus on the 2001 which was initially my parts truck lol.

I think the 2000 the prior owner did some wiring overrides as he changed out the driver door lock which key doesn’t fit and radio is missing.

 

I did the same with my Series 2A. The one I bought for parts became the one I put into service and drove for 27 years.