I have a 1988 2.8L Chevy S10 Blazer with a high idle problem. Its has 234,000 miles on it. Its all tuned up replaced IAC. It was up to 1050 RPM but have gotten down to 800. Can anyone show me a picture of where exactly I drill to get to the idle screw to adjust it. And after I adjust it I imagine I have to reset the TPS. Would I also need to reset the timing?