ok here is my deal. im having vac problems and cant figure out what is causing it. when i start my car the idle starts off at 1200-1300 rpms, after the car heats up to regular running temps it surges from 600 to 1000. i have replaced both tb gaskets, injector gaskets, bov gasket, intake mani gasket, and ic pipe to turbo gasket. also if i turn the ac on while the car is warmed up at idle it almost stalls and it wont idle above 600.

when doing a leak test do you set it to tdc or does it not matter? ive done a leak test and cant find any other leaks. all timing marks line up.

it was fine before i replaced the head gasket. my boost gauge read 20hg at idle before the head gasket replacement and now its reads 10hg at idle.

any suggestions or help would be greatly appreciated.