The levitational energy from his experiment was driving him insane making him steal and try to kill Giant Man (Bill Foster).
Air Walker was created by Bob Budiansky, Dwayne McDuffie, and Jim Shooter in Marvel Super-Heroes #11 - Fireworks
Arlo Samuelson was a down on his luck scientist living with his fiance Donna. Feeling compelled to be recognized for working on his Theory of levitation, he seeks out well known Scientist (and secret superhero) Bill Foster aka Giant-Man. After failing to get his attention at work in Stark Enterprises West, Arlo follows Bill home to present him with his theory. Disinterested, Bill took the papers but assured Arlo he did not take him seriously. Arlo returned home empty handed and disenfranchised. His fiance Donna having had enough sends him off, leading him nowhere else but to work at his makeshift lab. Arlo, lacking all the necessary components of his theory but dawning a protective suit he bought with his life savings, began testing his theory with the intent to use it on himself, being without the aid of animal subjects. The experiment goes wrong but it leaves Arlo in a constant state of levitation and with the power to levitate objects at will, but if he touches the ground he felt tremendous pain. He took this as a sign his power was unstable and that being grounded could kill him. Arlo driven mad by is failure and the "levitational energies" of his experiment, he begins stealing gold as a component to stabilize his condition. Bill hears Arlo's description on the radio (describing him as Air Walker) and realizes he has to stop him. Bill confronts Arlo mid rampage and tries to reason with him. Arlo having lost all respect for Bill attacks him thinking he was only jealous of the theory. Eventually Giant Man is able to get a hold on Arlo and literally grounds him. This discharges all his levitational energies removing his powers and returning his sanity. Bill offers top vouch for Arlo to the police and offers him a job at Stark West as Donna appears to reconcile with her once lost lover.
Powers and Abilities
Samuelson gained the power to levitate himself and other objects. He can also affect the acceleration and directions the objects move. He can accelerate a steel girder at a target or decelerate a falling helicopter or incoming bullets. He also seemed to smash the helicopter showing his powers may augment his strength but this is unclear.
Air-Walker's powers stopped working if he came into contact with grounded objects. His powers also may not work on living creatures.