Transmission not shifting properly, codes P1409, P0171 and P0174

So my vehicle listed above has been running great, especially for its high mileage. I've done a few long-distance trips in the last year (ranging from going from or to AZ or visiting family an hour or so away and back just last week) and haven't had an issue. Only thing I've had to replace is the radiator when it blew which of course threw a code the shop didn't have the right reader to clear, so I'm not sure which it is/was.

The issue I'm facing is after noticing the truck had an issue shifting a bit (just revving more than it should before shifting), I checked the trans fluid and sure enough it needed changed as it was more like muddy water colored then a ruby red. I drained it and changed it with new fluid, and it seemed to solve the problem for a few miles before suddenly sitting at a red light it wouldn't shift at all; just rev/red-line and occasionally just barely catch a gear so I could move off the road and into a parking lot. After letting it sit for a bit so I could at least try and get it home, it basically repeated this process with a great deal of struggle. From my (limited) experience if a tranny is going out, it's pretty obvious and gives some clear signs, not just going from perfectly fine to shot.

I checked to see what codes it was throwing and have p1409, p0171, and p0174. Not sure which of these (if any) was from the radiator issue, but these codes don't seem to do directly with my transmission itself so hopefully that's technically a good thing?

I know 1409 is an issue with the solenoid circuit (which is vaguely familiar though I'm used to working on much older cars such as my 1982 T-bird where everything has plenty of room to work with and dealing with sensors and computer crap isn't nearly as prevalent), and 0171/0174 is the PCM sees the air/fuel mixture is running too lean (too much air, not enough fuel) if I remember correctly?

I'm at a total loss and of course this happened on my way to work so I'm taking a hit to my wallet as it is and taking it to a shop to diagnose/mess with is a bit out of budget if I can help it. Sorry for the wall of text, just trying to be as thorough as possible with what I've got and reading through this web site for related issues this seems like thee place to get some reliable help.