Brand new carb-still problems, help?

over the years I have found that until I replace all the 40 years old parts with good new stuff, seems there is always a problem arising. problem is NOW, so many times the new parts are junk!!! ha!..... like VR, coils, plug wires. even an NOS carb that is 40 year old can have problems.
but like RRR said, until WE ( as in you and I and everyone else), can diagnose and rebuild what we are working on, we are at the mercy of someone else! Ha