I have replaced all vacuum lines including EGR tube and tried the cover the IAC control hole but the engine still runs. Drop to about 500 RPM's from 900-1000 and smooths out quite nicely I might add but the IAC error pops up. I would think if I have a vac leak that a suction noise would increase from the leak in order to keep enough air to keep the engine running. I block the brake booster vac line and the two lines running to the evap canister controls and all, it still runs. Where does the tube on the back side of the EGR control go to, is it vac? I could not easily pull it off so I figured I would damage it. I also have quite a gas smell at the fuel cap, I replaced it but still smells quite strong.
I also found by mistake really that Rodney Dickmans tube running to the PCV is a little long. The pipe goes so far into the elbow that it blocks the 90 degree turn, motor runs rough with the crank case can't be ventilated.
Thanks guys I did plug what I think is the same lines your both talking about. I believe them to be the lines that come out under neat the MAP that have the rubber connector were Rodney's tubes end change to the rubber hoses that that run along the truck wall. At the same time I block the brake booster and still no dice on killing the engine.