As you mentioned, corrupt proms have been found lately. Maybe it's an age thing. I'm not big on buying used electronics but I did pick up one last week. Mostly because the ecm was already unhooked and laying there and it was the exact same ecm as mine so it sort of looked meant for me.
If after some driving tomorrow the high idle issue doesn't improve, I will swap the proms.
This truck was my retired parents so no, it wasn't driven hard while they owned it. A long trip in that truck for them was an occasional 10 mile trip to town for most of the years they owned it.
I'm not big on additives and the like but I will try Seafoam.
The aldl was disconnected before I began adjusting the idle today. The laptop battery ran out.
I believe you once posted your version of the minimum idle speed adjustment procedure that differed from the repair manuals.
The Winaldl is only an easy way to get into OBD1 diagnostics that most likely falls short of what some other programs can do.
I'll post again with any improvements. Thank you CT