I have a 1988 Nissan Sentra with the 1.6L throttle body injected straight 4. I have rebuilt the motor, and have since come into contact with plenty of small things going wrong. About six months ago, the head gasket blew while I was driving it and I had the head machined to work right again. It has since always misfired the first couple rotations when I start it cold, which I assumed was because it was cold. Without warning it wouldn't start about a month ago and I replaced the coil and it started up perfectly. All of a sudden about a week ago the same symptom popped up and it won't start. Found some coolant in one of the cylinders so I pulled the head off. The head gasket is in perfect shape, but every cylinder has coolant inside, with 1 and 4 being the worst. Though I haven't seen any coolant in the oil, and the gasket is fine, I'm not sure what the cause of this issue is. When I pulled the head gasket off though, I noticed that quite a few of the holes for coolant ports had been blocked off. It looks as though it came like that from the factory, but I can't totally tell. Any ideas as to what might be going on?