P0335 and P0725. In need of enlightenment.
 

First off, I want to say I've read just about every thing on the internet that I can find with regards to these codes and the 02-06 Altima . I know of the recall(VIN doesn't qualify) and I've changed both the cam and crank sensors, as well as the spark plugs. I've also visually inspected both connecters and wires for as far back as I can see. All seems well. I've also cleaned the lugs and terminals on both the battery and starter. I'm not really sure what the next logical step is . I've tried searching exactly what "crankshaft sensor circuit A" entails, as in, everything involved in the circuit. Not much luck unfortunately. I will probably start ringing out wires before throwing more money at it, but I was fairly certain that the sensors would remedy the issue since it was such a common fix.
Just a quick overview on what's wrong with the car. Trouble starting. Cranks over at least a half dozen times before it will fire up. Sometimes it'll just sit there and crank all day without starting. It has yet to actually stall which seems to be the difference between me and a lot of people.
Any suggestions would be appreciated . I'm all ears.