If I were working on this car, the first question I would have is: Is the tach working when this problem occurs? If it is, forget about the CPS. If not then it is a possiblity. The other part of this discussion, I have never seen an O2 sensor cause a car not to run. At 220K it should be replaced but not because of this cutting off problem.
Report back about the tach when the failure occurs.

__________________
84 500 SEL (307,xxx miles)