[kfray]

With the ISV deleted the DME can not control idle speed. On a cold out side temperature day the idle settings you made may not work.
When you turn on the A/C the idle speed will drop because the DME uses the ISV to maintain Idle speed. I think you would be better of finding out what is wrong with the ISV, the ISV hoses, or the ISV wiring. A simple bench check of the ISV is to supply 12vdc to the center pin #2 and then alternately apply ground to pin 1 then pin 3. the ISV should shuttle back and forth passing air then blocking air.