Your computer reads reference voltage from the TPS. Should range from around .75 to 5 volts depending on the postion of the pedal/TPS.
If you take your foot off the pedal it won't set a code right? So a TPS can cause trouble and not set a code. Use a meter and make a back probe out of a sewing needle to check it at the terminals of the TPS. Sweep the throttle up and down and check it. If it's consistant and seems to have no issue it still could be intermitant