[4 L-bodies]

Is your set screw been altered, or is the plastic cap still covering it? Lots of people have trouble with the AIS motor and end up adjusting the the set screw in lieu of correcting the AIS issue. The TPS has somewhat of a preload on it, that is normal. Correct voltage should be around 1.0 volt not 1.5-1.8 volt. It is completely normal to be not horizontal.
The set screw was put in place not to be a idle speed adjustment, but rather to prevent throttle blade becoming stuck in throttle bore when in a closed position.

 

[4 L-bodies]

Just so you have something to compare yours to, here are two unmolested pull or draw through TB's. Set screws still have factory plastic cover intact.
FYI- Remember that the engine is canted several degrees towards the firewall too when your comparing this picture to yours in-car.