Hey man, don't buy anything, don't swap anything, don't throw anything away untill you read tps in a 99 p11 fsm if u need a 99 p11 fsm pm me and ill give u it. I recently delt with tps issue and I replaced a perfectly good tps and ecu bc I just read whatever people thought the issue was on the forums.
(not saying they are wrong)
Just read it and good luck, its about 30 pages worth of reading but it covers everything, from tps adjustment, power regulation to how injectors and the intake can jack up tps voltage. Also the ground on the ecu might need to be loosened then retightened back down. I'm quoting the fsm. Go read it!