I have a 06 at 175000 miles. I started writing and couldn't stop! LOL! Maybe this may be useful to you, no worries if not.
It may be something very easy to replace or fix yourself. I stopped going to the mechanic due to their shabby work. I've done a lot of work myself but your issue is something I would first get on YouTube and see if you can research it there or any other searches you can think of.
However, if it's not on the internet because it's not very common, then I would suggest you go to a Lexus dealer to let them diagnose it and then you have a direct way to fix and correct the problem. Believe me, its worth going to them to find the problem because it might just be a relay switch or circuit breaker.
Your dad gave you a great vehicle. If you are under 100k, then invest in repairing everything you can! I am expecting to keep mine till 250k or 300k miles. I might even buy a rebuilt engine at that point.
This may be something you should think about if you plan on keeping it.
I would immediately change the heater 'T's because the plastic breaks down, and it will do the same to you while on the road. There's two of them on the top center back connected to hoses with clamps. They send the radiator coolent to the back. It's a very easy job, and I would buy metal ones on eBay. It's one of two cheap products Lexus did to this SUV! The other is a plastic radiator spout the radiator cap locks on to, and it's definitely something to keep an eye on.
I would repack the front bearings if close to 30, 60, 90k, etc. Because that's their intervals. It’s a long job at first due to learning. There are plenty of videos out there to DYI. But at least, once you have done, you're set for the next 30k.
Make sure your CV's are still sealed and not leaking. If they are DO NOT buy aftermarket. Lexus has invested in these nothing compares to them. Therefore, before they go bad and are confirmed to leak, buy a new boot kit from Toyota (Landcruiser) or Lexus and rebuild them yourself! The kits cost about $40, and it comes with boots clamps specific to each boot and the grease needed! You'll need a special tool to clamp them. Don't use a universal clamp. Get the tool!
Re grease the shaft at all the grease fittings. The transmission fluid is sealed, but your warranty is over, so at 100k, check YouTube and change it! It's easy once you learn it.
Flush ACH, brake, differential, transfer box, and power steering fluids. It's all on YouTube, and it's easy.
Your speakers are probably busted from the foam discergrating. You can rebuild them all with a speaker kit cheaply. Don't worry about rotating your tires and rebalancing them only when your steering shakes.
It sounds like a lot, but you can group them and spread your hobbie over the next couple of months. Then you are set!
I'm from NOLA but live in Houston, so welcome to the greatest SUV ever made. If you need some suggestions, just place @sbcglobal.net behind my initials to email me.
As for having collision or comp insurance, the insurance companings will total it for a scratch. Meaning if its worth 5k that what you will get minus the deductible. Its not worth in to me. You may want to pass on it. But get your liability and buy uninsured as well. When they hit you, your insurance fixes it.
If you are not inclined to work on the car, then you may want to hire a mobile mechanic from Craigslist. They have better pricing on labor!
I hope this helps! Take what you want and leave the rest!