Just bought my first X5. New challenge to make it run:)

[Bmwe5320023.0]

Finally bought my first X5!
The body is in great shape, 0 rust whatsoever.
However it has a few issues that I would appreciate some advice with.

I apologize that this post is so long...

VIN: 5UXFA53542LP39173


The biggest issue it that the car will go into Engine failsafe Prog, DSC Inactive and ABS error all at once. Transmission Failsafe prog will also pop from time to time.

The car won't shut off but won't accelerate either if I press on the gas.
My only two options are to restart it in neutral or to pull over, turn it off for a few seconds and start again.


I was suspecting the battery and the alternator.
I unlocked the voltage on my cluster and drove around with the voltage display "on".
My voltage while driving the car was between 13.3-13.6. I'm thinking it's a bit low...but I didn't see any spikes. Although when the car goes into the limp mode, I lose that voltage display.

When the car is parked and I check voltage via cluster panel, it displays around 11 - 11.5 volts. Basically this should indicate that the battery is completely dead, yet the car starts at -40 no problem.
I checked it with the multimeter right away, and it's showing 12.3 volts.
I'm not sure if the cluster panel is displaying the voltage properly then...it's a big high quality battery that was replaced just last year. Likely cluster voltage readings are incorrect, because I know my multimeter works well.
I charged the car overnight at 2AMP and it's now reading 13V. This indicates to me that the battery charges fine.

3 days ago I drove for about 400 km after buying the car and it would go into this engine and transmission fail mode every few minutes.
If I turned the car off, put it in neutral and started it again, the car would drive for a long time at around 100-120 kmph. The RPM however would go to 3500-4000 instead of the normal 2000-2500 before the glitch. The DSC and ABS light would also stay on.
If I pressed on the gas pedal all the way, the car would accelerate super slowly.

Another option was to get off to the shoulder, turn the car off for 30 seconds and start it again. In this case the car would drive without errors, with normal RPM and without illuminated DSC. But this would only last for about 5-10 minutes. Then the car would go into that failsafe mode again.
If I restarted it in neutral while driving, the car would drive for maybe an hour, but would still die at some point.

Other glitches:
When I turn the light knob to off, the trunk lid unlocks for some reason

There are 2 oxygen sensors hardwired under the hood. The seller told me his buddy got the wrong sensors (apparently from a different model X5 and just hardwired them).

I'm not sure why, but the rear left side tail lights aren't working. The previous owner simply wired the left rear tail light directly to the right rear tail light to get the power from there.
Now all the lights work but I get these errors:
- Check brake linings
- Check brake lights
- Trunk lid open
- Check rear lights

I also know there's an issue with the fuel smell, it could possibly be related.
When filling the tank all the way to full, the fuel smell is very strong, both inside and outside the vehicle. The previous owner told me that he replaces the fuel pump (passenger side) but did not use the new o-ring for the fuel pump.
He also said that the rubber hose by the fuel tank filler hose is damaged.
The smell does disappear when the fuel level drops down to 3/4.
I'm wondering if the fuel pump is bad (he said he used a cheap fuel pump).
Another possibility would be the o-ring for the fuel pump being bad, which would create the leak and also drop fuel pressure.
Maybe if the DME senses a drop in the fuel pressure and the car goes nuts.

From what I researched so far, a common issue seems to be a gasket getting stuck in the throttle body between the maf and the intake tube, causing those issues. I will check it shortly.

Crank sensor is another possibility.

I scanned for codes with a cheap scanner, even though the engine light is off:

P0121 Throttle position error
P0221 Throttle/Pedal Position Sensor
The person who sold me the car said that the brake switch needs to be adjusted, as apparently it trips DSC and ABS lights somehow.
P0222 Throttle position sensor is reporting too low a voltage
P0455 Probably the leak by the fuel filler neck
P0505 Idle control valve
P0735 Gear 5 Incorrect Ratio
P1602 Control module self test
P1638 Throttle Valve Position Control; Throttle Stuck Temporarily

I included the videos to show what's happening with the car. They're all very short

https://youtu.be/LwVNbFrD8GA

https://youtu.be/GhabmivyCfQ

My thought is to start by checking the air intake boots and throttle body to see if there's nothing stuck inside (I've got an inspection camera) and to see if the plate isn't sticking.
Next I can try cleaning the throttle body, MAF sensor and the idle control valve.

Worse case I can simply replace MAF, TPS and ICV one by one and see if anything changes.

Please let me know what you think.