Still throwing codes at me

[nmikmik]

This thing is starting to drive me nuts. I know, I know patience & more patience, but c’mon.
I replaced the starter and ETCS while I was at it, fine. I replaced the thermostat because cooling system was filled with water & I am sure it was not distilled. I replaced the downflow oxygen sensor because it was throwing me an SES code & I couldn't pass the smog because of it. I did a “reverse slam” procedure down to the T and only improved forward shifting a bit – reverse still slams & if I am not mistaking a little worst. Yesterday I drove to the SMOG station to get it smogged and it did pass the smog although guys at the station said that some of the monitors were still not cleared up after I erased the last P0113 code. As soon as I drove off from station or as soon as it needed to shift into 4th gear transmission bucked and shifted into third. Not having experience with this kind of thing I drove it to the next exit, parked it and let it sit for about ½ hour then restarted and all was fine with exception of still reverse slam of course. It threw a P0773 and P0774 codes as well, so I reset them yesterday and drove again today to get the very same codes.
From reading around different treads it sounds like it could be
a. Higher voltage off the alternator
b. Something still wrong with new ECTS (or ECM is adapting to new things) ???
c. Valve body needs cleaning/replacement
Before I start throwing money in all directions I’ll try redoing the “reverse slam” procedure (I don’t believe I need to drain and fill fluid again, do I? And maybe do some harder than usual driving backwards on some empty parking lot, just to see if I can get it dislodged from whatever is holding it.
Any other suggestions?
oh, btw - the reverse slam i am having is manifests itself as follows:
when the car is cold and I put it in reverse it engages after a slight application of accelerator and of course it slams
when the car is warm it's pretty much the same only takes longer to engage and more rpms and it hits harder. I also noticed that if i let go of the accelerator just a bit while backing up, it will disengage and I need to hit it again. Just wanted to make sure I have a "topical" reverse slam and nothing"spacial"
Thanks!
update** - I drove it today for about 30 miles and no codes came up nor it downshifted for me. So I hope it's learning