T310mlr advice

[Orange cv713]

So my truck has a AI motor with a t310 behind it and it is honestly a miserable experience I live in the mountains of wnc and maybe 10% of my driving is on the interstate and that is not very flat but at interstate speeds for the most part is okay but any sort of slow moving as in 20 mph or under up grades and around switch backs is awful like embarrassing for one if you miss a gear you pretty much have to stop and restart but I guess my issue is most of the time I have to stop it is because I missed a gear which is pretty normal with this pos Trans and then on the restart whatever gear you start in you are stuck in until the hill planes out because maybe someone can but I am not able to ever up shift fast enough to keep the motor in its power range to continue on because you have to pause for a split second for the rpms to fall and by the time it will happily go into gear its way past being able to pull its self and as embarrassing as this is the other problem is I drive this thing every day and everyday is like my first day I can go for a hour our 2 and not ever grind or miss a gear and then if I grind it once it seems like that is the trend for the rest of the day up shifting is not honestly as big of a issue I have found if you shift around 1800 rpms it normally falls right in but down shifting on the other hand I normally only make about a hand full of down shifts with out grinding every day it honestly surprises me the times it falls in I have honestly found bring the rpm up slowly and trying to slide it in is normally the easiest, and the other issue is that if you leave the engine brake on up shifting is not happening but down shifting is okay as long as you dont miss but thats any truck, all this stuff sounds like beginner issues and I guess it is this is the only mack I have ever drove and if I would have known alittle more about it honestly I probably wouldn't have bought it just as far as the motor and trans go it makes me mad because I have drove trucks for about 10 year and I have driven all different makes and models and have never had any of these issues I have driven pretty much every eaton they make and it has always been smooth, any advice is much appreciated