97 explorer code 1744

I have a 97 exp 4.0 auto 5r55e truck runs great but check engine light is on so I can not get it inspected I pulled the codes and got a code 1744 tourqe converter problems I took it to the local ford dealer and he conformed the transmission was bad so I put another transmission in it drove 30 miles and the check engine light came back on pulled the code again and same code 1744. Trasmission shifts perfect tourqe converter engages and disengages just like it is suppose too. Thought it might be a ECM problem so I switched the orginal for one from the junk yard with matching numbers and still no luck.HELP