looking at the area you live in, id say start with the CCV valve and hoses...get the cold weather one ..
also look into changing the plugs, see if youve got any oil on the plugs, if you do, change the VCG's
fresh oil and filter change...
fuel filter as well..

Since you say that its overheating, check the hoses or the expansion tank..thermostat locked in closed position..or maybe its time for a cooling system overhaul..

You could always change all the fluids since you have no idea last time they were changed..
see how the motor runs after this small tune-up .

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2006 X5 4.8is LeMans Blue / creambeige interior
Prod.date: 2006-06-21