Wont rev over 3500 rpm and under hard accel. wont shift wont rev over 3500 rpm

do you mean you changed the engine speed sensor for the auto box ? works off the engine rev's this is not on the same line as the rev counter it counts the rotations of the shaft spining.

Due for a transaxle rebuild,common on that veh

The fact you continued to drive it when it won't
shift correctly & has been slipping, your done

there is a transmission sensor on the top of your motor by the intake. it senses the accelerator or motor rpm's and tells the ****** to shift. its about 30.00 and easy to change. get it at any auto parts store.

2 problems do not inter react , 2 and 3 gear relates to clutches or syncros or badly allined shift gear , 3500 revs points to gas problem of filter prob

You may want to have the catalytic convertor checked out. it may need to be replaced.They can cause a car to run hotter and have poor acceleration to the point that the transmisssion won't shift. Also fuel filter could cause this but not usually. Hope this helps please leave comment.

transmision is slipping

its either low on fluid or the clutches & bands are worn or need adjusting!
DONT REV IT!
get itserviced QUICK SMART! & check for leaks!

It wont rev past 3500 in driving?
The governer on these is set to NOT allow a higher rev when car is stopped and not in gear.
Try to change oil viscosity or filter manufacturer.Some filter manufactures put in a bypass valve that kicks in too early.

if your run no air sensor it wont rev past 3500rpm as it would not richn the engine under load

You may have a clogged fuel filter, change it and retest. Also check the air filter to see if it is dirty, replace it if you shine a flash light through it and the light is very dim om the opposite side.