To state the obvious, we only know what you’ve told us about the Tahoe. Having said that, all things average, a Tahoe in good – average condition is worth about $2,000.00 according to Kelly Blue Book.
I agree with Weight. You state it would cost 4,000.00 to fix it. But getting several estimates might show it’s more or less money to repair. It might also reveal other issues you’re not yet aware of.
This may not be what you want to hear, but on the bright side you found out about this before you made your journey. It’s one thing to be stranded but more complicated if you are disabled.
Being disabled myself, I would be hard pressed to make a trip just after purchasing a car, even new cars can have issues. As mentioned before on these threads, this is a good reason for having an emergency fund, more then $3,000.00 often sited. It’s routine for auto-shops charge $100 or more an hour for repairs before the price of parts.
This doesn’t help you at this point, but for anyone buying,,, if you need a safety inspection to register the vehicle you’re about to purchase; I always have the car inspected before I buy it. I tell the owner, okay deal, I’ll pay for a safety inspection whether it passes or fails, if it passes we have a deal. If it doesn’t pass you can re-negotiate or pass on the deal. Either way you’re going to pay for an inspection, why not do it before you own it.
Try to slow down, a few months may offer a different perspective and options. There lots and lots of parts for these trucks and nearly everyone works on them.