My wife's blazer started idleing really high about a year ago, so much so that it would bark the tires when you put it into gear. First thing I check was the egr but it wasn't stuck open, then i replaced the IAC valve and it would still idle high, the blazer had alot of miles on it so i decided to replace the intake manifold gaskets, that led to deciding to go ahead and pull the heads and get a valve job, which led to rebuilding the engine because i found a bent rod, you can see the rebuild process in the "build" section. anyway, everything is back together and it is still idleing very high, i can get it to idle down if i pull out the valve in the IAC so thats it's completely closed and dont hook up the connection. but soon as i connect the IAC back up it will open and idle really high again. I dont like throwing parts at something so I took some voltage reading of the TPS, MAP, and Coolant Temp Sensors here's my results

Engine off key on

TPS +5.03V -12.56V Closed +0.88V Open +4.56V
MAP +5.03V -12.56V Off +4.84V Engine running at high idle 20.5 in Hg +1.12V
Coolant Sensor Disconnected +5.03V Connected -12.56V Cold at 65 degrees sitting over night +2.58V Hot 195 thermostat open +2.11V

Any ideas would be appreciated, Thanks in advance.

 

what would be telling the iac valve to be opening up, maybe bad computer?