2000 blazer LS 228k miles.

The list starts here.

I have a misfire on cylinder 1 new plugs and plug wires.

I have an issue with the transmission or something affecting it. At 30mph and above I occasionally have what feels like it slips out of gear. My rpms might fluctuate anywhere from 100 to 200 or 500 to 1000. Or it loses gear clompletely and revs extremely high into the five grand area.

Added transx to the tranny fluid fluid and I have more power to the wheels and it has at least masked one of my symptoms. Putting into reverse the vehicle wouldn't move until revving engine up.

My efficiency is suffering terribly. Average of 10mpg at the moment.

pcodes are as follows
p0301
p0420
p0440
p1870
also an intermittent crank positioning sensor code

just put a new fuel filter, plugs, plug wires, 4x actuator(I have 4 wheel now), vacuum lines that needed mending.

The tranny needs a flush and filter and the pan is dented.

im sure there's more but i can't think of it now. If you need more info ask and I will answer.if anyone has thoughts I'm willing to try just about anything that isn't a new tranny.
(edit)

Ignition is increasingly harder. I put in a new battery from schwabs. Sometimes it will crank right over and start other times it will crank and crank before eventually grudgingly start. I have to add heat to every tank to make sure it starts in the morning. I added sea foam to the last tank to try and clean it up. Injector issue?

i also have a missing cat and o2 sensor. Someone before me removed them and put in a flexible stainless section.