SMP are better than most of the cheap aftermarket brands, but I've still had my share of non working parts from them... and part life doesn't seem to be that good.
It just isn't worth my time anymore to roll the dice, so when it comes to sensors, I buy Mopar (Delphi/NGK/etc).
If my dealership can't/wont give me a good price (always give him a chance), I track down the part online.

 

Bought a mopar IAC on eBay for 65$ and the truck is back to purrrrrrrring again