P0452 Buick- cause of choking out and almost stall and engine light?

Question

full power after a few seconds with air conditioning off

Answer 1

P0452 Fuel tank Pressure sensor circuit low

Yes this will cause the choking and the stalling. what happens is the 5 volts refference is shared with other sensor such as MAP (manifold absolute pressure) sensor,the MAF (mass airflow) and EGR valve. if there is a short bring the 5 volts refference low you can expect drivabilty problems. Clear the code test drive the vehicle with out the a/c on. if there is no drivability issue  test with the a/c on. if the drivability issue return you may have the a/c pressure sensor causing the problem.