07 Toyota Camry 2.4 misfire problem

I have a 07 Toyota Camry 2.4 that recently had a misfire.  I
used a code reader which informed me cylinder one had
misfired and was in need of a spark plug replacement.  I
replaced all 4 spark plugs just to be uniform and while
inspecting the plugs I noticed cylinder 1 had coolant inside
the cylinder where the spark plug sits. The remaining
cylinders had no coolant.  I pumped approximately 2
ounces of coolant out of the cylinder number 1.  This
vehicle had the engine rebuilt and new radiator installed
approximately 1 year ago and has vibrated excessively ever
since then to the point I had to take it back to the mechanic
who installed motor mounts and tranny mounts.  The car
ran with less vibration however it was still noticeable. Also
noticed the passenger motor mount needed replacement
again so I replaced it as well.  My question is does this
sound like a head gasket leak or intake manifold leak?  Any
info would be greatly appreciated.  Thank you.