1998 xc-70 what no start issue will be next

[Clockboy]

So I've had two no start conditions in the last month. The first was the fuel relay - of course it happened while I was away on business and my son and wife were in the car. The second was the cam sensor. That one occurred while the expeditions engine was apart while doing intake gaskets and I just needed one more part. So my question is since these things are common issues are there any other ones that I should be thinking about. My son will be coming home from university and for whatever reason his presence causes at least one of the cars to break. I'd like to get out in front if possible.

[abscate]

cap
rotor
plugs
wires
clean the IAC
Do a complete VAT inspection on the vacuum hoses and replace the crumblies.

[Clockboy]

All done already. Maybe sir jinx-a-lot will have a running car the whole time he is home. Thanks.