Crank position sensor circuit "A" code after replacing CPS

My cel came on and I took it to Oreily to get it scanned. Scanner said crank sensor. Later that day the light went off and stayed off for a couple of days before coming on again. This time it stayed on a day or two and went off again. A few days later it came on and stayed on. No noticable change in my truck. A couple of weeks go by and one morning when I get ready to leave it starts fine and runs normally until I back out and start to pull off. When I start to pull off it stutters a little and catches up, I let off and start to go again and it stutters again and dies. After that it just turns over without firing. So I replaced the CPS and it still does the same thing. Scanner still says crank sensor circuit " A" . The scanner reads rpms when trying to start it. I'm lost, ANY help would be GREATLY APPRECIATED!!!! THANKS IN ADVANCE!