Quote Originally Posted by SlowGrind View Post
Tomorrow I'll take a look at the timing again and check for vacuum leaks. When I changed the spark plugs they all looked pretty good except one was oil fouled just a little.
It's entirely up to you, but "looking at the plugs" is not a compression check or a leak down test. This is what I was talking about. It may be a hassle, but a diagnosis is only as good as its foundation. If you skip the basics or don't check them properly then you could be correct in your guess and save yourself an hour or two, or you could end up chasing your tail for weeks because you hoped it was good and it was not. A leaking valve will not usually foul the plug, but it will show with a leakdown test and most likely show with a compression test if its bad enough. The typical scenario from a shops perspective is the customer thinks they know, try to fix it and by the time it gets to us there are a lot of new parts on the engine that may or may not be installed correctly. The customer is now upset with all the money they flushed and the basics have not been checked properly. It was not always the simple stuff, you could gamble, but you don't know unless you are very methodical in your approach to the problem. Just a little info, to try to help you out.