bigern45

having major diagnostic issues with a 2001 nissan sentra, ses light on , occasionally stalls, wont start , tach jumpy. code P0335 for crankshaft position sensor a comes on as a pending code almost as soon as you start the vehicle. the shop that worked on the car before me installed the crank sensor kit that nissan sells as replacement (three pieces, one crank sensor position, one cam sensor phase , and i think a cam sensor phase). when that did not fix, apparently tried to rewire the sensor as a fix, which did nothing as well. to cover myself, i again rewired the sensor, installed three new aformentioned sensors from nissan and still have the same issues. i collected information with a lab scope and am getting a perfect pattern from the crank sensor, a simple on off pattern ranging from 0 to 3.5 volts dc. there are 17 on off signals , then a skip on the 18th, and i assume at 20 degrees each pulse gives me a perfect 360. so no problems mechanically with the crank shaft or electrically with the sensor. i then removed the computer and checked the voltage on the crank signal return inside the computer on the circuit board and i have the same perfect pattern, identical to the one directly out of the crank. but then from the computer to the tach i have again a dc current on/off signal, but at times it is glitchy and drops out when it should not. i am wondering if i could have an intermitten open in the computer before the crank signal gets to the main information transfer (or what ever it would be called). apparently the computer is getting a poor signal and it seems good all the way up to the computer itself, so i deem the computer faulty. can any one help me confirm or figure out what is going on with this nightmare?
i have already checked and retightened numerous grounds and check ignition positive to the sensor as well. any help would be greatly appreciated.