Toyota Repair: Please help, throttle position sensor, toyota tercel

Question
My fiance and I own a 1984 Toyota Tercel station wagon.  The car is an automatic 4 cylinder.  About June the starter solenoid went out on the car so we had this changed.  The person who changed the starter and solenoid somehow screwed up and now the car will only start with a wire that is connected to the starter.  This was the beginning of our problems.  While the car was running one day it suddenly stalled out and when restarted it would not stay running unless you kept your foot on the gas. We tried adjusting the throttle cable and the carburator but to no avail nothing helped. The car started and ran but then began to overheat and is still overheating.  We then took and rebuilt the carburator to see if that helped but it did not.  During the reconnection of all the wires and hoses a piece that went to the overflow tank and hooked onto the carburator broke.  We took the piece to an auto parts store but they could not tell us what it was.  We were told that the piece was called the "throttle position sensor".  Would such a piece cause the car to run at a very high idle...I mean the idle on this car is so high that if it slipped into gear it would probably end up going 80mph!!!!  Please help if you can....any advice would be gladly appreciated.  Thank you.

Answer
It sounds like something on the carburetor did not get put together right and the throttle is sticking open, remove the air cleaner and look down into the carburetor to make sure both of the butterfly plates on the bottom are fully closed, if one of them is open you need to find out why, there is something wrong that is holding it open, the throttle position sensor may cause a high idle but not more than about 1500 rpm so there is something else going on that is causing this condition.