Transmission downshifting issue?

I'm a bit surprised that there isn't any code yet. I only have an ABS light on. A prior code of C0110. The scanner says there's no current code but when I try to turn off ABS light it comes back on the next cycle.
Otherwise, there are no codes. I pretty sure I mean downshifting. Maybe I have the terminology wrong. When I press on gas pedal and speed up the transmission usually downshifts? When it hits 3,000 RPMs to about 1,500-2,000 RPMs. Now it's going all the way up to 4,000 RPMs before it downshifts or sometimes not at all and I have to feather the gas pedal to get it to downshift. It does this for the next gear too. Sometimes when I press on the gas it just bogs and I have to floor it to get through the intersection or to switch lanes.

I'm starting to think it's a transmission solenoid but not quite sure which one.

I believe it is the original trans. I bought it used and there weren't any records. The fluid was dirty and maybe a 1/3 of a quart low.
I changed the fluid and filter. And put in some lucas stop slip hesitantly because I knew I might have to do it again to replace solinoid(s). It didn't solve the problem.
Is it possible that the speed sensor on the rear rear wheels could be causing this and my ABS light to come on?
My scanner doesn't have Can Bus so I tried having some of the auto parts stores scan it and they didn't detect and codes either.
So I suppose it's probably a solenoid problem.
Some answers say it might be the 2-3 or a pressure solenoid. I thought I saw that solenoids weren't that expensive so maybe I should just replace both?
Sorry if I'm not really quick about all this. I have a ruptured disc and sciatica that is slowing me down majorly. I'll wait for your next thoughts before I start throwing parts at it.
Do the trans repair stores have a special scanner that wouldn't cost alot? Or would it be cheaper to try and buy a scanner with Can Bus reader? I thought I heard someone say that there were some on Amazon for $35. I haven't looked but it sounds good to be true. When I bought my scanner I'm pretty sure a Can Bus scanner was about $500.

Thanks to everyone that replied.

My scanner did have can his for brakes. I can turn everything on and off. So does this mean it's probably a voltage issue or the pump is faulty?

The wheel speeds worked, were all equal, and matched the speedometer. I put new brakes, rotors, hubs, and sensors on the front last year.
All valves and feedback were off. DRP was not active. The ABS stop state was off. The ABS relay was on. Differential pressure was okay.
Other DTCs listed under ABS were.
C0035
C0550
C0201
U1041
C0040
P0306

I'm not sure how to check these. Do I use my meter and plug it into the various sockets?

It turned out that my transmission and eventually lack of power issues were all caused by a clogged catalytic converter. And I never had a DTC until the truck barely moved. After it warmed up it would gradually get slower and slower. Begining around 40 mph until it would just stop. I verified it was clogged by getting a loaner bore scope from AutoZone tool program. I removed the position one oxygen sensor and fed the cable in that way, when everything was cooled down. You don't want to melt it in there while your exhaust is hot.
Thanks for your help 2carpros!