Random stalling and/or running crook and hard starting are just some of the symptoms of a bad/faulty CAS.. Check for any logged error codes, also, if possible, check the code history for CAS error codes that have set and then cleared by themselves.
(you need a scantool to check and clear error code history.)
Error codes 46, 47 and 49 are all error codes related to the CAS. If you dont know how to check for any current error codes yourself, have a read through the posts and check out the pics in the link below.