i am wondering what is wrong with my tansmission if anything and what could be done to whatever problem i might have..

i have an 86 camaro sport coupe with the original base 305 and the stock transmission (700r4 or 200r4) idunno which one 133000 miles

when i drive around town in drive the car is pretty much fine except for when i go up hills the transmission upshifts to 3rd gear at about 30mph and then gets stuck there untill the hill ends or i lower the throttle and floor it getting the car past this period. in overdrive it is much worse

when i go up a hill in overdrive the car bogs down like before in 3rd and then gets stuck at an even lowr rpm in the top gear. it feels like the car doesn't have the power for the bigger gears. also when i am in overdrive the throttle "jumps" when i accelerate to highway speeds. once i make it to 60 or so the car steadies out but while accelerating the car seems to slip or not catch the big gears right
i hope this is clear cuz i dunt really know how to explain it
also i tried to see if the tv cable was causing the car to shift to early but there was no improvement

is my tranny slowly going bad? should i change trans fluid? is it the torque converter? is my car bogging down because it is underpowered? what is my problem?

any help would be apreciated

 

With 133,000 miles on it. Rebuild is the only thing that makes sense. Repairing unit with such high miles is only delaying fate. Include a new (rebuilt) converter in the budget when the time comes to freshen the trans.