I have a 2000 dodge caravan 3.3l automatic.

I was driving it the other day and it just jumped out of drive, into neutral. I had to shift back into drive in order to continue onto my destination. it has done that twice already. I have been out in the van since then and it not do that. but it does shake in spurts as if the clutches may be slipping. I have called autozone about this problem and the guy said he almost guarantees it to be the shift interlock. does anyone agree or know of anything else it may be? also if it is the shift interlock, where is this located and is the shift solenoid the same as the shift interlock?