Hello and welcome to JA, the idle should be 750 rpm =/- 25 for automatic trans and 750 rpm =/- 25 for manual trans...when you are checking the timing, make sure the spout connector is unplugged....the symptoms sound like the IAC valve is sticking...with the engine at idle, unplug the IAC valve, and see if the RPM drops, it should be affected when the IAC is unplugged, if it does not change, then the IAC needs to be replaced.
no you do not have to disconnect the IAC to set the timing, you have to disconnect the spout connector, this is a little plug right next to the distributor. The IAC needs to be unplugged to verify that it is able to control the idle. Recheck the timing with the spout unplugged and let me know...
The PCM should stay with the engine, so take the PCM from the donor truck and put it in the truck the motor was put into, then recheck
yes, the 2 wire plug is the spout connector