Idles high after going from park to gear and back.

[ChevyTech]

35 Kpa would be about 10.3 inches of mercury which is low
58 Kpa would be 17.12 inches which is good
68 Kpa would be 20 inches

I guess it is possible that the torque converter is not free enough causing a drag. The only other thing turning is the transmission pump when it is standing still while in drive.

Something is wrong when the idle is up at 1500-1700 and the IAC count is not dropping.

I would switch between data readings, and writing down the readings, and looking at what all changed when it is running at the high idle speed verses at normal idle. Look at what the ECM data shows for RPM, coolant temp, system voltage, as well as the MAP and IAC count. Make sure the run time keeps going and is not reseting. Make sure it shows that it is being shift into gear and back to park.

If the ECM and PROM are new and good something has be be causing bad data.

WinALDL makes that easier to look at all the readings at once but if you write all the readings down you can get close to the same thing, and start comparing sets of readings. The bad part is it does not sound like what you are using gives as many data readings.