i just did a oil change and now my car wont go past 2000 rpms what happend why on 2001 Infiniti QX4

why it wont speed up

2 answers
I had a problem with my qx4 not going over 2000 rpm and it was the telling sign that my head gasket was about to go out which it did.
It wasnt going over 2000 as a way of protecting itself.
You may have inavertantly knocked a wire connector loose somewhere. Check closely in area of air cleaner and that duct work. The Intake Air sensor is a possibilty that you could have disloged something there perhaps.