Expert: Robert Summers - 12/29/2007

Question
i have a 1991 chevy S-10 with a 4.3 v6 throttle body injected i replaced all hard and rubber vacuum hose i replaced the fuel filter and fuel pump .the map sensor and just recently the IAC or i think its called the idle air control sensor . i put the new IAC sensor today because before it would start and then die and then i would start it again and i would push the gas this time and it would raise rpms and then bore down and die so i asked Robert a chevy expert on this site and he told me to check that sensor so i did once i start it it runs exelent until i put it in gear then it will slowly drop rpms and then die what is wrong

Answer
Hi Robert... did you clean IAC when you replaced it. use only a good air intake cleaner...also check the EGR valve, make sure it is working. another common problem is a plugged cat converter, it will cause the same problem...if you suspect it try disconecting the exhaust at the manifold and try running truck. if it runs and revs ok after you disconect the exhaust replace the converter....hope this helps