What problems/fixes are there for a P2128 code?

What is your question?

P2128 tripped and causes limp mode. Goes away but comes back intermittently. Replaced accelerator position pedal sensor(entire pedal) and occured again(check engine light and limp mode on start after driving a short distance, going into a business for 5 minutes and coming back. Code was again p2128 and after cleared has driven fine for a few days but I expect it to return any time.

How long has your 2006 Saturn Ion had this problem?

Few weeks