Well I fixed my exhaust leak and tried to chase down a missfire. I ran through and disconnected the injectors one at a time looking for a change in the idle. Pulled # 8 and no change. I felt the injector while plugging it back in and felt it start working again, so I moved on to spark. Pulled the wire while it was running and it's getting spark. There's a knock/rattle type of noise coming from that area (the back of the DS head) so I'm going to make sure nothing has come loose such as a rocker or someting. Everything else is running fine and it idles down to 900 no problem. I also checked the coolant tank for bubbles and all I got was cavitation when I revved the motor (that's normal right??) there's no smell of hydrocarbons in the coolant tank, nor is there any smoke coming from the pipes. Any suggestions? I might try to get it on a compression tester and do a leakdown on it, but I wanna try and narrow it down before the weekend.