OK i have redone my intake manifold gaskets i have checked for vacuum leaks found none.While idiling at 650 rmp she holds a steady vaccum 20 high. Mass air flow meter flows +- 7 gps. The iac runs at 16 steps. She idiles perfectly for a1/2 hour. Then when i take it for a cruise +- 3 miles when i park and put her in park she just starts to hunt for an idle . The revs would hover at +- 1500 rpm the iac extends to 150 steps and the maf shows +-16 to 19 gps.
Has any one experienced anything similar. I also noticed that once she is warm and you restart her there ia a spark knock /pre ignition . Can anyone shed light.

 

i am experiancing kinda the same thing, had my computer tuned after a head/cam in stall, idle set at 875 rpms., it did for a while, now it idles at a constant 1100. iac counts aren't at zero so i know i don't have a vacumm leak. putting a throttle body on thursday and will be taking off my intake manifold to port it for a 58mm tb so i will be putting on a new gasket, hopefully thats my problem.
-Jason