I have a 2001 ford f150 supercrew 5.4 liter v8 engine 4X4. We recently replaced the intake manifold about 3 or 4 months ago. It had had a cylinder 4 misfire for the longest time now. We have change the park plugs and the coil packs on every cylinder. It went away and came back shortly after. We couldn't figure out what it was but then another problem occurred. Now I I drive it for more than 15 minutes, the engine temperature gage goes all the way up to hot and spews antifreeze out the resivior cap. We've changed the thermostat 2 times an the resivior cap and it still did it. Then we thought there could be some air pockets in there from when we changed the manifold. So we've been running it with the cap off of the coolant resivior and squeezing the hoses and inside the resivior air bubble keep popping up ten they would stop so we thought we fixed it. It worked good for a while then it started spewing antifreeze again and over heating. We've done this 3 or 4 times and now we are thinking it's something else. Hopefully it's not a head gasket causign the misfire and the over heating or a crack in cylinder 4. There was no antifreeze in the oil, the oil was fine and for some reason it just keeps over heating. I don't know whether the cylinder 4 misfire could be connected with it overheating or what. Anybody know what to do? Hopefully I can get out tomorrow and check the radiator and stuff but I'm pretty darn sure it's working fine.