Hello,
No Range Rover (Or ANY Landrover for that matter) will be completly without problems. I own a 4.6 P38 because I love it and nothing else seems to hit the spot for style and comfort.
Things to look out for when you buy one:
Suspension air bags - are they worn? (typically last about 70k before they are worn out).
Engine problems - large oil leaks, water leaks, etc. Check all oils incl. gearbox oil.
Rust - especially the chassis. Get a good look under the Rangey.
Exhausts are not that great unless there is a stainless steel system fitted.
Wheel hubs are expensive to replace (£300-ish) when they go (typically around 100k I understand - I'm not up to that mileage yet...)
Aircon system - does it work? Check for a "book" symbol in the aircon control display - this indicates a problem.
Check ALL the electrics - windows, sunroof, etc. Heated seats often give up working...
Then check all the usual things you would look for anyway when buying a car.
Check for service history - fuller the better (especially if done by main or reputable LR dealers).
Having said all that - they are REALLY great to drive! I will not part with mine now!
This is a great site for help and advice if you get a P38. I have a P38 simply because I've always loved them - and I like V8s! I know it can be a (sometimes expensive) labour of love - but it's well worth it!
I hope you decide to buy one in the future - just look around for a good, well cared for example and you will not be disappointed!
Karl.