Idle problem 88GT Speed Density

[chuck88]

I hope someone out there can help me I had a low idle problem stalling with or without AC on (with AC on stalling out is almost a definte. So i heard that the best way to fix this problem is to drill a 1/4' hole in the butterfly on the throttle body, so I did now the idle is to high. I tried adjusting it down (the idle screw on the throttle cable) and it goes to 1200rpm and no lower and now the throttle feels sticky when first tapped. Any help would sure be areciated.

Chuck88GT

1988GT 83k miles GT40 upper/lower lower is ported
equal length headers, 2 1/2' dynomax exhaust,
65mm throttle body, cold air intake
Speed Density