As you can see below I have essentially the same rig that you (36B) do. During the first year I had a problem with delayed 1st / 2nd shifts and the transmission indicator flashing.
The fix was additional grounding for the computer. There was a service bulletin that covered the problem. I can look up the number tomorrow. It seems unlikely that this problem would take 7 yrs and many miles to show up ... but just a thought.
I'll try to find the codes that were stored and the SB number and PM you.
BTW ... knock on wood, only problem with the chassis so far
Roger & Gail
Golden Retriever "Captain", Maltese "Annie" Labradoodle “Piper”
2000 Pace Arrow Vision 36B