I’ve got an 04 Impala with I believe the 3.4l and the torque converter lock is stuck after 1st gear so it doesn’t stall. I can only imagine it’s the lock solenoid or the pressure switch but I’m not sure. It seems to change either I’d have remove most of the front driver side to get to the transmission cover, correct?

The kicker here is the fluid. At 250k+ miles and probably never having the fluid changed it has lost all color and is gray. I know changing very old fluid can be a gamble so would I cause more problems with having to stop the fluid back off?