I have power coming in to my box I checked power at main and it is good until I turn any of the breakers on then I loose power at main then when I turn breaker back off the power at the main come back up

Classic high resistance connection somewhere. A TYPICAL spot is the split bolts where the utility wire attached to the service cable before the meter. Likely the Utility's problem.

Are you losing LINE power into Main Breaker, and if losing both hots under load would be stranger. Could be in Meter Can connections as well. Measure both hots from neutral/ground.