First of the the min idle is set too low. Does the idle control work. Vaccum leaks.?
1. What is engine Vacuum at idle 18 inches are specs'
2. What is ing timing ..
3. Are there any codes/
Check those and get back to me.
My advise is why did the dealer change the computer? If it was to fix you low idle then they need to it back in their shop.
Let me know. Jim
This should be more info needed not an answer..