Was this a dual run/start capacitor? Did you use the same size and voltage rating?

Yes Mike, Its a CD 40/5x440R it is the same one I replaced, this will be the 3rd capacitor to replace on the unit. its going to be 87 here in North Carolina today, BOY! i need to figure out whats wrong?..could it be a bad Motor? i just got? the motor is the same RPMs ect. ......Thanks (( Charles ))

It could be a bad capacitor. It sounds like the start capacitor is working well, but the run capacitor could be causing the fan motor to overheat and shutting down. The fan motor itself could also be the issue.

Run Capacitor? there is only one capacitor. so they sold me a bad capacitor...again. I'll go buy another and try it

You have a dual capacitor. It is two capacitors inside one can. The 40/5 mean 40 micro farad/ 5 micro farad. One capacitor is for the condenser, the other is for the fan. I am not sure but they may be both be used as a start capacitors.

Right way to diagnose this is to take voltage and current measurements rather than swapping parts.