Not to question the repairs performed but did you happen to replace the main rubber lines with new hose clamps? If these were overlooked it may explain the trace amounts of air you are getting in the system, as well it could explain the intermittent power loss.

I had a very unusual 210 vehicle that was plagued with an intermittent dying problem. Based on that experience I would like to leave you with one odd thought. Are you able to perform a voltage drop test? If so check the negative circuit between the battery terminal and the engine block during cranking, and then when driving the car. (should not exceed .500mV) Fluke 88 has a min/max record function that is extremely helpful during this test. If I hadn’t discovered this problem myself you would be hard pressed getting me to believe that a loose cable connection would cause a dying problem while having no affect on the starting circuit.

An experience you simply do not forget!