Sometimes i get a sudden feeling like i am about to pass out. a nanosecond in duration. followed by stiff neck and general tiredness. possibilities?

Positional changes?: I wonder if these may occur when changing position, such as rising up from a seated position? I wonder if you could be mildly dehydrated - it is summer, and you're located in 'the heart of Texas'. Try increasing your fluid intake and see if still present. MVP can do 'funny' things too, so if no relief, you may need to have your heart checked in more detail - such as for transient arrhythmias.