2001 Aurora 4.0 with P741 code, 80K miles

At first tranny was lazy about shifting into 4 gear. Now, it does not shift into 4th at all. Scan code is P741. Otherwise, the car drives and shifts 1>2>3 just fine. Converter lockup just not taking place is the way I read the 741 code language.
Took it in for a complete flush, fluid and filter change in tranny and torque converter. Code after being cleared persists.
Now what, valve body rebuild, another tranny, what? Keep clearing out the code and keep driving and hope errors goes away.
Otherwise, it's a great car.
bink

I have the same issue with my 02 v6 @ the same mileage.
From what I have found it looks like rebuild time, just putting it off since I don't drive it every day and thinking of selling it.

The trans should be scanned with a trans function scanner to check solenoid functions and tcc application slippage errors.