Engine rebuild

The car was run without coolant and stopped running. Coolant was added and tried to start the car multiple times. It was noted that there was air bubbling up in the reservoir tank. The first sign that there may be a blown head gasket if not more damage. The motor taken down to the block, the cylinder walls were perfect with no blemishes or problems, the crank moved the pistons without rattle or any issues. The heads were cleaned, resurfaced, and tested and were fine. The engine then was put back together with meticulous care. Each part was cleaned and put back on according to Chrysler specifications. Draining the oil there was a considerable amount of coolant in with the oil. The drain plug was left out for a while to be sure every drop of coolant was drained. Fresh spark plugs were put in also. The only way to start the car was to press the accelerator pedal to the floor to "purge". It starts this way but will not idle, or start without purging. However, when it ran there was a large amount of coolant pushed out the tail pipes. Should I take off the exhaust system and drain it out? Or has running the motor pushed out the coolant? In addition, are the oxygen sensors now fouled and need to be cleaned or replaced, and would the idle air control module make it hard to start and keep running?