P0123 - throttle position sensor circut high voltage (immature)
P01121 - throttle position sensor circut intermittant high voltage (history)(immature)

When I watch the throttle position sensor it goes from 0-100% I'm not sure if it's releated but for the past year it used to be every now and then but now its all the time. When i'm going about 80 kms the rpms surge and you can feel it in the truck while driving. The rpms go anywhere from 200-1000. Now back to the throttle sensor, long story short I broke my origional one getting the alternator off. Since I live up north, its a week for parts so I went to the wreckers and took a used one. Nothing has changed so I ruled out the tps but am now throwing those 2 codes and having my doubts. What are the chances of having 2 different messed up tps's? So back to the question with the codes, what do they mean?