Give us more information.
Manual or auto trans. (I'm assuming auto by your "not in gear" comment)?
How many miles on the clock?
How does it perform under part/full throttle? Do you notice a lack of power? Has the CEL come on since you replaced the knock sensor?
How long have you had the vehicle?
And, finally, you said "tune up with all the basics." This means different things to different people. Could you elaborate on what was replaced/inspected?