My car will not go past 30 in drive, but it will if I manually put it in 2nd

Hello, Not what you want to hear, but this is likely failure of internal transmission components, or the transmission control unit (computer) has failed. If your check engine light is in, have autozone scan it for codes, and post them here. That will give us a better indication of what is going on. If the vehicle is in limp mode because of another issue, that would make sense as well. 1996 and up + problem = scan. Let me know what you get back.