Howdoo and welcome.
Main thing with the v6 is timing belt and tensioners. Renewal is 40k or 4 years, irrespective of what you may be told otherwise. If no history or proof then would suggest factoring this into the price. And it must be done with the proper setting tool. Tippex markings etc simply is not enough.
Cam covers leak. Not due to warping as most will say, but due to blocked breather system. replace only with genuine VX parts and not from a factors/ebay, otherwise it will need doing again in very short order.
Prefacelifts rust under the window rubbers on the doors as well as rear arches.
Skuttle drain blocks on the passenger side under the pollen filter allowing water into the front passenger footwell. Can also reach the rear footwell if car parked uphill!
Secondary Air Injection pumps can whine like a jet at takeoff when cold. Lasts for 30 seconds or so but remedied by unplugging and removal. Can be a good bargaining point though.
Wishbone bushes wear and cause camber issues and easily wrecking the inside of a tyre in a few thou miles. Bones can be rebushed with poly or replaced entirely.
Read through the howtoo guides. 99.9% of the jobs are already covered.
