318 rpm drops to 400 in gear WHY???

Crane cams is who he got the cam from recomened the tci 2500 stall converter . We tried run the idle up to 1200 rpm and does the same thing when droped in gear .

We just switched back to the first holley 650 that he had on the car before the rebuild that ran perfect to see if that would change and boy it did cant turn the idle below 2,000 rpms or it will die. So looks like were going back to the new carb . ???????????