u/Next-Insurance2606

hi there, I recently changed the throttlebody position sensor on my 1994 Mustang GT as the code was being thrown (122 i think). I replaced it and it ended up making the idle pretty high, at around 1.5 K and it also is throwing the 998 code which I believe means it’s in limp mode. I also believe when I’m in reverse neutral and drive that the RPMs are on there are also higher. Why would this happen? Any ideas? any information is appreciated.