Not shifting in 3 or 4 gear

What is is causing this is a faulty, damaged, or otherwise inoperative TCU or Transmission Control Unit. Very simple fix that most anyone can do with a proper diagram. If you are able to get hold of a graphic diagram you simply have to disconnect the battery, take out the two plugs that plug into the bottom of the computer, and replace the unit. If you are going to do this yourself I would advise spoending a very small amount and purchase a "Memory saver" so that you will not have to worry too much about the car having to "Relearn" itself. you can usually pick a decent TCU from a junk yard for anywhere between $50-$125.

Good luck and hope this helps.