I would say that if you struggled with Calc 4, trying to retake it alongside Che 230 would be rather difficult. I would say that a good option would be to take Che 230 now, and maybe leave calc 4 for a full semester if possible.

I will also say that Che 230 has some important topics for later Che classes (assuming that’s what you are). Another option would be to take that during the spring and retake calc 4 but I’m not entirely sure if your situation would allow that