Ok so after a little time dealing with idle surging and other driveability issues like p0300 and lately with high idle, I changed out the iac. There was still no change in the idle surging, and it actually seemed to get worse. So after thinking back to before I put the new heads on (it was running good before that) I figured everything had to be from when I changed the heads. Yesterday after work I decided to dig into it a lil bit and redid the ground on the thermo housing because it had broken before and I fixed it but this time I cleaned it really well and soldered it. I also noticed that where the injection spider comes out of the top of the intake didn't seem like it was seated well. After putting a screwdriver between the fuel pipes and the intake and pushing up slightly I noticed about a 1/4 inch of movement on the side where the fuel lines go into the injector body. The other side seems to seat with no problem. After numerous attempts at trying to get it to seat without yanking everything apart, I improvised. I got a square washer and used a screwdriver to carefully pry up on the fuel line hold down and insert the washer between the fuel line hold down and the top of the manifold. The curve of the fuel line actually helps to hold constant pressure on both sides of the washer to help hold the injection spider in place and create a seal. I'm not saying this is a perfect solution but it has made a big difference in how my truck runs, because it sealed a vacuum leak that I really couldn't find, maybe because a lot of small leaks were harder to find than one larger one. I guess this is why I found silicon in this area when I took the intake off to begin with. So if you ever have to take off the intake, make sure it seats good when putting it back on, I thought mine was fine but now it runs so much better after putting in my little (fix). In short, it's a bad design, so don't neglect checking it just because you put a new o-ring on it....
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