tps or ecu?

my 96 sunfire seems to have a lack of power and will bog going down the highway, a code was tripped for low throttle position sensor voltage, i replaced the sensor to no help. I checked the voltages and all were within the correct range. I disconnected the tps completely and the car seems to run normal

Did you have 5v to the sensor? Did you buy a cheap part?(if so, return it and buy a good one) Check for a bad ground to the sensor by backprobing the ground on the connector and touching the other lead to the battery negative. Do this with the key in the on position and all connectors connected, you should have no voltage. If you do have any voltage across the wire, try cleaning all the grounds you can find.