Cars does fine for about 20 miles. Then if i stop it wont go forward. If i put it into reverse than drive again it will go. It also clunks pretty hard when i do that. Not sure how to retrieve any codes either. What could be going wrong with it? Its a 94 Taurus GL 3.8 v6 auto

 

Your Tranny is shot. Mine (98 Merc Sable, 3.8L V6) was slapping hard into 1st & downshifting same way. I put a bottle of Lucas Trannsmission fix in that has helped, it only shifts a little hard when downshifting. No way around it though, it needs a rebuild, plates must be worn out...

 

If it's the original tranny, it possible the forward clutch piston failing. You probably have the AX4S tranny in your Taurus since you have the 3.8L V-6. Ford didn't resovle the problem until 1995 model year when the finally built the clutch piston out of steel instead of aluminum