Saturn Repair: sputtering and stalling, saturn sl1, injector pulse

Question
toke car to nissan they changed starter siad that was the problem.. all codes where gone after they changed starter...but as soon as i picked car up drive one block it stared doing the same thing..it was also reving very high..toke it back..because of the year of the car didn't want to spend to much..they said they found a used starter is that possible...how do i know if they did change starter...i've already spent $400 getting parts that did fix problem..please e-mail if you have any advise-------------------------
Followup To
Question -
92 saturn SL1 ..... drive along in city and then the tach needle would jump radically, up and down ... sputer and then stall ..... Will take several minutes and attempts to restart .... another time after stall .... it was reving at 3000 rpm but  did not kick down for several minutes ...... does it in the morning  and then sometimes good all day .... garage ..... read code for the knock sensor ..... rare that the service engine light come on ..... only happen in city .... some times after restart, barly touch gas and it will stall ..? any idea's.coil and plugs recently replaced .....
Answer -
HI IS THE ONLY CODE THE KNOCK SENSOR?
WELL WITH A BAD KNOCK SENSOR U MAY HAVE A INTERMITANT IDLE PROBLEM BECAUSE IT WILL RETARD THE TIMING AND CHANGE THE INJECTOR PULSE WIDTH...IT IS VERY POSSIBLE THAT HTE EGR VALVE IS GETTING BAD.. FIRST CHECK FOR MORE CODES AND WE WILL HAVE TO FIX THE CODE ONES FIRST. GET BACK TO ME

Answer
hi the starter isnt the problem if the car is stalling and reving high they also cleared the codes when they disconected the battery. a starter will not cause a high rev either a vacume leak somwhere or a sensor giving a improper reading i would talk to them to make sure they know the symptoms.