I have a 90 Isuzu Trooper 4cyl with almost 190k miles. Recently had the head resurfaced. Now it's been running great for a few weeks then suddenly it stopped holding an idle. My dad says it's not advancing properly or has a vacume leak. I can't find a leak. But I cant find the info in the Hayes Manual for advancing. It will turn over but even flooring the gas wont keep it running. If you could, help me understand the Hayes manual, or even better help me find other ideas, and how to check them. . Thank you