This works on the V-6 engines. Jump the ADL with a paperclip, just like checking codes, turn ignition to on position, after 30 seconds disconnect IAC connector, turn key off, **** disconnect ECM fuse and negative cable. Reconnect IAC connector, fuse, and then battery cable and turn ignition to the on position for 15 seconds, then turn ignition off. This will now reset the IAC to a known key-off "park" position. Now start the car, the ECM should be able to control the idle but will still need to be driven to learn some other values.
*****(Normally on V-6 engines, once you capture the IAC and disconnect connector, you'll start engine and play with plate screw to get the lowest running idle, a scanner is highly recommended.)
87 Duke engine has dis ignition, if car still doesn't run properly (within reason) you may want to pull plugs and check wires. As I have been thinking about this today, your temp senders have alot to do with how your ECM regulates the fuel mapping but you said it's a reman, should be good.
I would love to know what the fuel pressure is at. Didn't GM make it tough to check fuel pressure, no Von Schrader valve like the V-6 engines.
Maybe this will help, if not, it's another bump, maybe some other rmembers will chime in here for you.
EDIT,,, See if the auto parts store has a loaner program for fuel pressure testers, the fuel filter connections seem like the logical place to hook up to test.
[This message has been edited by jetman (edited 11-07-2007).]