Chevrolet Repair: 2000 malibu starting issue, reading issues, sensor readings

Question
i've got a 2000 malibu here with a 3100 in it.  once its up to operating temp, if you shut it off, then start it again, it will rev up to 2000 rpm, drop to 800, rev up to 1500, then to 500 make one more quick attempt to rev up but then it dies.  125,000 miles.  no codes exist, idles fine otherwise (sticky IAC valve?).  Power steering reservoir is in the way of checking fuel pressure (probably going to have to do that).  Looking for ideas from somebody else before I start digging this apart.

The odd part is that it only does this when its at operating temp, and there isn't any codes.

Answer
Hi Brandon... check the temp sensor... install a scan tool and see if temp climbs normally and reaches operating temp...if not replace it...if it doesgo up normally then when it reaches operating temp shut it off and restart... watch the temp sensor readings and see if they are irratic...if they are replace temp sensor...if that ok .. try a good air intake cleaner and clean intake and iac....because it only does it at operating temp i would be inclined to look for temp reading issues...hope this helps