1992 T-Bird Trans Problem

When OD, at about 40-45 mph the Transmission goes to Neutral, But in D, everythings fine, however its like driving a 5sp and only you cant get out of 4th gear. Anyone know what the problem is?

Hello norsemen73. I was hoping someone that is more knowledgeble in transmissions would answer your question before now. Since not, I would recommend checking with tccoa.com for an answer to your question. Sorry for the delay but good luck!