I just swapped on some gt40p heads that had some work done to them and have been converted to stud mounted 1.6 roller rockers and along with a gt40 intake manifold onto my 95 mustang gt. I used hardened stock length push rods as the heads had guide plates. I have the valve lash set to about 1/4 turn after there was no up and down play between the rocker and lifter. I could have gone half turn but the polynut was already pretty tight. Anyways, after buttoning up everything i decided to see if everything is okay and runs. Well it fires up and runs, but the at idle it shakes wayyy to much for having a stock cam. Never like i had before i swapped the heads or intake. Im at a lost. Im not sure if maybe a lower manifold gasket slipped causing a vacuum leak or maybe i have the incorrect valve adjustment? The mid pipe is not hooked up but that shouldn't affect cold start idle (open loop o2 sensors)? I had primed the oil pump before i even set the lash as well just to make sure the lifters were pumped up. The car revs and sounds fine at higher rpms, just at idle the engine is shaking too much. Idle rpm is steady smooth at about 1000 rpm. What do you guys think this could be?