You may want to check around on the compression guage. I got a nice one for about $32 at an Advance store. When testing the compression, remove all the plugs, and then test each cylinder. It will be better if you can look at the guage while someone cranks the engine. You should see max compression on the first or second stroke for each cylinder you're checking. All the cylinders should be within 20-25% of each other. If you have a lame one, squirt some oil or tranny fluid in the spark plug hole and then re-check that cyl. If the compression improves, the rings are leaking. If the compression still sucks, it's valves or other leakage. Good luck.
