P38 4.6 lumpy tickover /diff oil leak

Hi,
New to the forum and considering buying a friends P38 4.6...lovely spec, 54k, W reg, autobiography interior, dvd etc but I am troubled by a lumpy tickover around 800 rpm. I also noticed a slight oil leak coming from the diff at the front. FInally, there is a check manual warning light when the aircon is operated, however, the aircon works perfectly. Could these be potentially nightmare/expensive problems I am buying in to?

Thanks for any advice.
Phil

Probably not too expensive,the lumpy idle is usually leaky vac pipes on the plenum chamber and a quick reset of adaptions on the engine ecu.Also a quick check of oxygen sensor outputs on a live data display.At 54k they should still be ok - probably just a quick sort out.As for the hevac showing a fault this is a bit more of an unknown,could be sensor faults,blend motors or sticking distribution flaps.The hevac system on Lp RR's is very fussy and just about any one of 20 odd different fault codes can put up the book symbol.Lucky thing is they are not all too expensive to sort out.

just read your post and my w reg has exactly same probs without the oil leaks can u tell me where the pipes for the aircon pump is coz i read somewhere else on here the pi[es can split going into the pump