3 IAC valves in a row?

I have a 98 trooper which I had serviced due to check engine light and was told it was a bad IAC and from experience had to agree, ( it would stall run real fast at rest or park etc etc,,.) well the IAC was replaced and all was good for 3 months and it just went last Tuesday. took it back to Pep boys and they serviced it and again everything pointed to IAC well they put a new one and 10 minutes later it went bad, so I went to advanced looking for a diff brand IAC figuring Warner was putting out bad IAC and the guy there stated that the chances of getting 3 bad IAC was slim he said something could be causing the IAC to go bad or read as a bad IAC when it is not. Can anyone help?