My Westerbeke 13 refused to start a couple weeks back. After a few days I found a poor connection to the fuel pump and replaced it. While checking for the problem I opened the fuel filter and also cracked the first injector. After getting her running again I have a new problem where after running for 15 minutes or so the rpm's will drop to about quitting and then she heads back up and continues. Never dies, just drops off. I'm thinking perhaps air in the system but I don't know how to bleed her to find out. Does anyone have any ideas on this? Thanks in advance...now to the clogged head.