2G intermittent misfire help

[1kick]

hello again im having a strange problem im thinking its fuel related but im not sure i recently replaced my head gasket and head rebuild due to overheating my engine and now i have a misfire that comes and goes so im going to try to explain what i have noticed after letting the car ( 97 gst ) sit over night it seams to run fine until i get into around 8-10 psi it misses or stutters i cant really tell after 20-30 minutes of driving it starts to misfire at idle and while driving which i can sometimes make go away if i run it to 6k in 2nd gear and let off it smooths out the other thing i have noticed is when my idle stays at 1k-1500 it will not misfire normally idles at 7-800 so i dont know what that is about the car is mostly stock it has an intercooler and a k&n maf while the car is missing i have pulled the injector wires one at a time to see if anything changes and it does it gets worse same with pulling the spark plug wires compression is ok 130-140 warm check engine light will not come on with any misfire codes the only code i had was the egr which i forgot to reattach the vacuum lines to thats fixed now has anyone had this problem before thanks