Thanks for the response.
I was particularly lucky in getting the Q4 as it was bought by my local Alfa specialists, "to give the guys something to keep them busy over the slack winter months". They hadn't had much opportunity to work on a Q4, but I have used these guys for years and both of the owners are Alfa Trained Mechanics, one being the Ex - UK trainer for Alfa. Anyway, the upshot is, I watched timing chains (all three), the bottom pulley and crankshaft sprocket ( both had to be cut off as Alfa had not used any copper - grease to prevent seizing), water pump and all guides and tensioners (bottom one came from Vauxhall as Alfa would not sell it without the oil pump attached; whereas Vauxhall would), replaced. The actual guys who did the work were VAG trained Mechanics and another worked for VAG in the German Works doing Component testing, (which were modified on the basis of Feedback from dealerships, where stats showed particular weaknesses, or failures of components. The car had been known to them for years as the owner, a company director, had it regularly maintained by them. The guy was so fastidious about maintenance, to the extent he became a bit of a pain in the bum. However, as one of the guys said, "If you are going to buy a second hand car from anyone, he's the guy to buy it from". For a moment I thought he was talking about me, so I can understand where they were coming from as my view has always been, "if it's not right, it's not right".
The plugs have been changed, but I do not know about the Lambda Probes. The air filter has been changed but my son bought me a K&N, which I will have fitted soon. The engine was flushed twice with flushing oil after the engine work, but I do not know about the state of the MAF. However, the emissions, when recently MOT'ed indicate the burn is "clean" - in the context of the diagnostics. As for the ECU, I would not know where to start with that one - way over my head. The handbook says 400 grams (I presume that equates to half a litre) of oil per 1000 kilometres and on reflection, it is just about doing that, or perhaps a little worse. It has been suggested to me, the valve stem seals may be perished and leaking a little oil into the cylinders and/or the exhaust manifold but I am not unduly worried. I shall have them overhauled in the near future, if there is convincing evidence to indicate this to be an issue. Otherwise, the engine is silky smooth and pulls very cleanly with startling progression throughout the rev range in all gears and the kick in the back when the cams start to advance is a real eye opener. It's not Ferrari like, but it gives more than a hint of what this engine is capable of - lovely. It's an Alfa Engine, all the way down to it's cotton socks. So the Block was made by GM, so what!, everything else is pure Alfa. It's like baking a cake, one can have all the ingredients, but it's how you use them, and "If Alfa made cakes, they would probably be the best cakes in the world". My Busso GTV has thirty thousand miles on the clock - had it from almost new and it is Brilliant. But it's not dragging 1740 kilos around. Horses for courses and the 159 V6 deserves to be respected as a genuine successor to the genius that was Snr. Busso's creation. It is worth remembering, the 156 had a Fiat steel block and the diesel JTD common rail came from Fiat. Lets not be too harsh. For many decades, Rolls Royce's were American V8's. I believe Henry Royce said "Take the best designed engine in the world and make it better". That is exactly what he did and "Imitation is the sincerest form of flattery". Now I've gone of on one, so I need to re-focus on the whole point of this post - How to ensure my Q4 is as good as it gets; I'll rely on you guys for that.