Low power, and possibly transmission problem
 

My 98 dodge automatic is having some issues. I took it out of the shop, and as i sped up everything shifted fine but it wouldn't go into overdrive, or go into 4th gear at all. The reverse works fine and the first three forward gears work fine too, but it won't get past 55 or so. Then my other problem is, is i notice that when I tried to climb a slightly steep hill it didn't have any power to climb. I put it into 4wd and into 1st and it still wouldn't climb. The tires wouldn't spin or anything. The rpm is up and everything but it wouldn't have the power to move. Please help!

First thought is to check the fluid level. Next, you will need to look at the electrical signals for the transmission. Look and see if the computer is commanding 4th gear or not. Also see if its commanding lock up. From there, you could have a bad OD/Lock Up solenoid, could have burnt up the OD clutches, have a bad speed sensor or possibly have a bad PCM.

K, do you have an idea on how hard, and how much it would be to repair if it is one of those problems?

PCM is about $1k, plus needs to be flashed for your vin
OD clutches can lead to a complete rebuild due to loss of fluid pressure to other critical areas. $2-5K
ATF is like $6 a qt
OD solenoid $100 ish, but you have to pull the VB to do it. While there, do the Gov press solenoid and transducer as well. Another $120 ish.
Speed sensor I don't remember but its not bad.
Biggest thing is you need access to a scanner that can read the PCM live and see if the PCM is commanding the transmission to act normally or odd. Also, with that you can check codes to help eliminate problems.