P0776 Engine Code: Need experienced advice

I have a problem and need you fine gentlemen's help. My truck threw a P0776 code on my Ultraguage (pending code, it did NOT throw a CEL yet). My truck would redline at 5500+ RPM in 3rd gear (at which time I would let off the gas and look for the 'tick' in changing of the gears in the RPM dial, but the 'tick' never happened). I pulled the truck over, check inside the engine bay, all hoses appear connected. I let the truck sit off for a few minutes then started it up. The pending code threw again on the UG, and I still let the truck sit for a sec. I preceded to drive home slowly and the truck shifted just fine, on time, in the proper RPM shift points as usual (between 2-3K depending on gear and speed).

The code threw after I had to quickly apply breaks at 70 mph (down to roughly 30 mph) for a car doing a u turn in the middle of a 6 lane interstate. When I went to apply the gas again, slowly, the truck bucked and the RPMs went to the 5k+ mark. Then the UG sent the pending code. This has happened 1 or twice in the past couple months but never threw a UG code. After looking it up, it appears to be a possible shift solenoid that relays the xmsn gear to the ECM not communicating effectively (which makes sense). It is an automatic with about 75k miles on it. what are your guys' thoughts??? (didnt trip the code on the way home after it was working correctly, which really makes me think its just the solenoid being faulty).

http://www.autocodes.com/p0776.html
^^^ "possible symptons: transmission shift shock"

Also this: https://www.tacomaworld.com/attachments/cia758-pdf.103583/

you guys have any experience with this?

 

Did you ever find the fix for this? Did you have to replace the SL2 solenoid?