How long does the crank position sensor last
 

Hello all. 1st time saab owner. I have a 2000 saab 9-3 trubo convertible. HAs a problem with cold starts. This is what I have done:
1. changed spark plugs
2 Change gas filter
3. Changed fuel relay
4. Checked fuel pump - Comes on when you turn key and ran wire to hear it on
5 . Spray quick start in throttlebody and she starts right up and purrs like a kitten. Drove for 40 min. with no problem and power is there - doing 75 at least. Turn it off and poof.
Now I changed the CPS in 6/2012. Is it common for this part to be faulty and need to be done again or could it be something else. Love to hear your thoughts