Chain of problems... related or not?

[alexmish]

I've recently had a chain of problems, and just wondering if those were related events, or independent issues which just happened to manifest themselves in short period of time...

* CEL event - problem with EGR valve, replaced, reprogrammed computer
* Next day - 4x4 error event, the steering wheel angle sensor did not re-calibrate after reprogramming... censor recalibrated
* Next day - diesel fumes smell for 5 minutes after cold startup - found crack in the EGR cooler, around where EGR valve connects (as per SA) - EGR cooler replaced
* 2 days later - CEL again, this time Air Mass Flow Sensor is bad, sensor replaced...

X has been fine since then for almost 2 weeks and 500 miles...

I am just wondering what are the chances for all these things to go bad immediately one after the ohter... I think they might have cracked the EGR cooler while replacing the EGR valve, but Air Mass Flow sensor going bad shortly after that?

For those of you mechanics, what is your take on this? Are these things related in engineering sense or in close proximity to each other? Any known/past experience with event chain like this one?

Thanks!