You'll find that if the tires are spinning the trans can't shift fast enough even though it's commanded at a certain rpm. You may have to lower your shift points well lower than desired until you get it shifting where you want. If you zero your shift timing that won't fix it. Quite often you also will have a problem with the converter being alot looser as boost comes on which can create a shift rpm problem. I would still use the mph shift points once you get the rpm where you want it. Traction is very important in trans tuning. If you're spinning alot you're wasting your time tuning the trans in usually. You can first tune it like you would the engine, what I consider open loop trans tuning.

Zero out shift timing
Lower shift mph down alot.
Dial in your shift points in the rpm table to the desired by running from a stop and going through the gears. Don't bother doing it from kickdowns yet.
Get the trans pressure's set where you like the shift firmness. Only set them when the trans is at normal operating temps. Do this for wide open throttle and part throttle.
Next go back through your logs and set your mph shifts in. You do this by matching up the speed and rpm that your desired shift point occured at in the log. From there set your wide open throttle upshift points 2-3 mph less than that number. (this only works if you are shifting at the right rpm at this point).
For downshifts, also use the logs. Find the highest rpm that you think you'd like the kickdown to occur at (commonly between 4000-5500 depending on setup) and look at what the mph is in that gear at that rpm. Put this number in your downshift settings.
For your shift timing, this is when you can put these back in. They can be helpfull in keeping trans temps down by running no more pressure than the transmission needs to make the shift at that desired shift time. Lower rpm/lower torque settintgs don't need to be at say .150. That just commands more pressure when it's not needed and therefore creates more heat. Fade the shift time to a lower number as torque rises.
Next take the truck out and test all of your new shift points again. With the shift timing back on it may take a few wide open runs for it to shift how you want it again just as turning a maf and closed loop back on does for a/f ratio's.
This is just my advice, not sure if will help.

 

Hhahahahahahaha. To Mangled03gmc comment!

 

Holy **** Zippy gonna take few days to absorb that much info.