Any issues with camshaft/crankshaft position sensors in 09' mercury sable?

What is your question?

I own a 09' sable. It has a little over 82k miles on it. Within the past month ive had to replace the bank 1 camshaft position sensor and the crankshaft position sensor(replaced both at the same time). Engine started running really rough and shut off 1 time while driving. Then i had to replace the bank 1 camshaft sensor again this week. Mechanic said it was possibly a bad part because it had the same code as the first time it was diagnosed but it ran fine with no issues for 3 days then it started shaking again and running rough again yesterday. I cant imagine that 2 new sensors would be bad. So Ive made another service appt. There have been no major engine issues ever with this car. No crashes of any kind. And we keep up, meticulously, with the regularly schedule maintenance. The mechanic said that a vehicle like this with such low miles, even for its age, should not be having these kind of problems. Im very concerned that there may be something more seriously wrong with it.

What makes this problem better or worse?

N/a. Consistent

How long has your 2009 Mercury Sable had this problem?

A few weeks