Im new u can say new booty butabout a 240sx anybody pleaseeeeeeeeeee

[al240sx]

i own a 1995 nissan 240sx automatic and i got the check engine light on code p1605 and my car seems to be stuck in a gear or shift seemd like when in at 60 mph or so rpm stays at about 4.the code means something about a/t tcm but what can i look for or do to fix it and is it becuss of that error code my car reacts like that? Any help i will really appreciate PLEASEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!!!!!