my 220v circuit breakers show a voltage but dont seem to be able to drive a load. why?
If you've bypassed all the controls in the stove itself, and the voltage still drops to zero when you apply a load, then there's either a bad connection somewhere in the wire run, or one of your breakers is bad.  (And breakers do go bad.)  I'd replace the breakers, (fairly quick and cheap) and if still no luck then replace the wiring run from the panel to the stove.