Ok, I finally found the Shokaku. It was not really where anyone led me to believe and, in fact, it was just pretty much a coincidence that I stumbled upon her.
Should I say where she was? ...or is this a closely guarded secret so as not to provide any plot spoilers for new players?
I actually sank her on my first try. I was amazed. I gave her a spread of all six forward torpedoes and then tried to high tail it. I have no idea how many fish hit her and how many misses I had because things got SO chaotic in just an instant! It proved to be a kamikaze mission on my part because Shokaku's destroyer screen plastered my tail as soon as I set my fish loose. I guess you could say that I killed the Shokaku posthumously.
It seems as though, UNLIKE merchant convoys, ALL the ships in the task force were pinging me. Did ALL IJN military ships have sonar during the war? By the time I poked my periscope up for a quick little peekyboo, all task force members had already gone into a pre-ordained game plan to hand me my a..se.
Of course, I had done a game save just when I discovered the sonar contact that turned out to be the Shokaku's task force. I have gotten to where I game save every time I get a sonar contact. It seems like a lot of trouble but it has sure saved my bacon many times. So, I went and played it all again so that this time I could kill her and then ACTUALLY ESCAPE!! Nope, it wasn't to be. It was almost as though the entire task force was telling me:
"What? You want to play this over again? Well, we'll just see about that!"
I had ships blowing me up, shooting at me and even ramming me if I got in the way. I had one big cruiser just chase me down and when I thought I had gotten out of her way, she turned hard to port and completely tore off my conning tower. So that mission is also on
eternal patrol. I think I got killed another six times before I figured out a plan that worked.
Finally, I learned how to kill the big flattop and live to tell it. But this brings up another question. The only way that I have found to survive in such a lopsided shootout is to follow this protocol:
#1. Get ahead of the task force and wait in ambush.
#2. Get below the thermocline, go to battle stations and rig for silent.
#3. Carefully map the sonar contacts - ALL the sonar contacts. It does no good to fixate on one or two. The fastest ones will obviously be the DDs.
#4. Wait for the fastest sonar contacts to pass overhead and continue. If they circle back, I might as just well reload the game and play anew. There is absolutely no way to shoot a DD off of my tail because they're coming in from several directions at once. And JEEEZE they're fast! I play this with absolutely zero time compression and I still can't react fast enough. So, I've learned that if they pass overhead and then circle back, I came up from below my thermocline too soon. (Yes, it's always MY FAULT!)
$5. Once the fastest sonar contacts have passed overhead and continue on their way, I have to watch the other nine contacts coming down the throat three abreast and then guess which one is Shokaku. I have only mere seconds to line up the shot and take it.
#6. Come to periscope depth, watch the depth gauge to open all tubes before the sub reaches periscope depth because there isn't going to be time after I go to the periscope to open those doors. But, as all of you already know, I can't open them when the sub is still too deep.
#7. Line up Shokaku and let her have all six forward tubes. Or all four stern tubes if pointed the opposite way. I don't know how many fish it takes to sink her but I just want to stack at least SOME of the odds in my favor. I give her all I can just in case some of my fish run stupid or I just plain miss. And there won't be any time to shoot anything else anyway. So, I see no point in taking torpedoes back to Fremantle.
#8. Make like Pink Floyd and
Run Like Hell. 
So the question is: If I find myself behind the task force, what are the options? During one game, I actually set about beating a path around the shorter side of Borneo in an effort to get ahead again. Once I got to where I just KNEW the task force would be, I patrolled for a week and then told myself to just forget it. This game is GREAT but it is not so sophisticated that I can use some sort of genuine three-dimensional tactics such as trying to outsmart a task force half-way across the Asian theater. Apparently task forces pop up and then they later vaporize into thin air.