2001 montero ltd intermittent dies or no start
 

Have a 2001 Montero limited 250k miles with an intermittent problem which can occur randomly may go a week month or 6 months between problems !
It all runs fine normally but occassionally it wont start (turns over fine) or may start then die a couple of minutes later,
if it is ok after 5 mins it wont give problems for days weeks or months
i can usually get it going by resetting obd codes disconnecting battery for a couple of mins and unplugging then re plugging in the crankshaft sensor.
some times the fix works for months other times just minutes.
it usually generates bad crankshaft sensor code and sometimes bad camshaft sensor as well as various misfire and emission codes but some times no codes.
has had crankshaft sensor replaced twice.
have had this problem at least 2 years...
2 garages cannot find the problem as when its running its fine.
I am thinking engine ECU but cant prove it,
has anyone had similar or know of a permanent fix..

Driving me crazy as its my work vehicle