In hot country, Volvo recommends 40,000km change for timing belt. I'm buying parts for mechanics to do the job and would like to have advice on the following:

1. Should the tensioner (also known as bearing?) be changed at the same time.
2. Should the water pump be changed at the same time?
3. What else needs to be fixed eg hoses that makes econimic sense since the labor cost would be not much of a difference? By the way what about radiator and its lifespan?

Of late I noticed if I step hard and the accelerator and let off quickly, the lamda light blinks and twice the engine just stop but could easily be started without any hassle. Could it be due to the dirty Idling unit (Known as CIS)and dirty throttle or a sign of CO2 sensor failure?

Current mileage 228K km or about 130K miles running in prefect condition admittedly having spend considerable amount of money in the past on maintenance. Hope to keep it for another 10 years. This is my 4th Volvo having owned previously 240GL, 740GLE and 850GLE but simply prefers to keep this 940 Turbo for many reasons. Guess you may say that I am a Volvo lover but please never recommends the S series as it loses the Volvo touch and never as unique. Guess 940 is truly the last of the real Volvo that is available.