Wow! There is a lot more to it than I thought. Two of them, figures. Ok, car starts but when driving it will seem to stall for a second then keeps on running. On the highway it feels like it is shifting back and forth between drive and overdrive. Which lead me to believe that the ECM was going bad. (Happened on another GM that I owned, had to replace that one every year. Also had to replace the cam$haft $ensor magnet on the cam$haft it$elf on that one) But then I noticed it doing it on surface streets and realized that the motor was acting like it was loosing ignition or fuel for a moment then recovering. So I took it in and had the codes run on it. Code was P0336. Which the nice man at the store told me was a crankshaft position sensor. He also advised me that it was the only error code being shown. Temp of motor, time that it has been running, outside temp does not seem to be a factor. So the next question would seem to be, Does the code tell us which sensor of the two is bad?