Well, might as well update. I recently got a chance to replace the coolant temp sensor. That fixed the cold start issue completely. Now it's just dialing the fuel in I think, which I'm going to take it somewhere to do. I've tried doing with with the DMM on duty cycle and it's just not working. I've got it about as close as I can get the main fuel mixture screw eyeballing it by how it sounds and reacts, but I'm still going to take it toa shop I know of and let them fine tune it. A friend knows them real well and used to work there for a bit, and they specialize in oldr Mercs, so I trust them to not screw anything else up.