Hi there, welcome to the board...
As Simon said, the O2 sensors on these are fun, just when you think you got em, 2 more go. But I should be good for a while - I've done all 4.
The tranny flush might help your shifting -- also, I know mine is a bit reluctant to switch up gears sometimes, but I am also used to a 5 speed, and waiting for the truck to decide its time to finally change is annoying sometimes... (oh, you wanna go fast now? well, okay, I suppose I can do that... hmmm... *gear change*)
Our trucks are pretty reliable, I think you can expect to be able to put many more miles on your engine if you take care of it.