charging problems

I have a 94 firebird LT1 5.7L,car sat for a couple of years everything from hoses to shocks/struts,batt,alt.,water pump has been replaced and is pretty much back to factory standards.one problem i have is it will not charge at an idle until u give it gas.and when parked overnite the battery is dead by mid afternoon.new parts are not always 100%,and had a problem with the last new alt. and got another cause the diode went bad.is there something posibly making the diodes go bad.and im not seeing it?

had similar prob with my 91... turned out it was the kicker box drawing power when key was off. check for any key off power drains or defective switches....radios , power seats, etc