I have had bad luck in the past using complete spring assemblies. The springs were often the wrong size. I replace the spring now and don’t use assemblies. It sounds like the suspension spring is either too weak or your cannon pinion is slipping. If the clock is stopping there is probably something inhibiting the train somewhere like a bent pivot etc. Does the escape wheel tooth snap to the next pallet when it drops off the previous one? I don’t think a sluggish clock will effect the time keeping (not sure). Does seem like it needs a stronger spring.
Just a guess,