Idle rough, then stalls. when a/c is on high. Also while driving suddenly jerks like loss of power
Sounds like the A.C. compressor is siezing.
Are the radiator cooling fans operating with the A/C on? If not, it could be that the head pressure in the A/C system is getting too high and bogging the compressor down.
That is only a guess as much more info is needed to narrow it down. Other than the above, rough idle and stall could be an Idle Air Control valve problem and jerking at speed could be an ignition miss, fuel pump/pressure issue, etc, etc. etc.