I need some help figuring out what to look at for this problem.

It is a 97 12 valve diesel with automatic transmission.

When you start it, you can put it in gear but it won't move forward unless you put it in reverse and drive backwards for a few feet first. Then when it does take off, it won't shift into the upper gears. It roars along in 2nd or 3rd (sorry, I'm not sure which) at about 40 mph until it finally slams into the next gear. Then it will run normally. This has been getting steadily worse over the past couple of months. I'm told it is the torque converter, but no one can say what is wrong with it. Do I need a new one? Or is it a part? A seal?

Recently it stopped shifting into overdrive also. Do you think I'm looking at 2 separate problems or just one?

Thank you for your help.

 

Does it drive forward if you go straight into manual low gear instead of drive? Without putting hands on it, it is hard to troubleshoot.