Tons of white smoke

[[ion] C2]

Mom's Pontiac Montana with the 3400 engine is having issues. Rough idle, TONS of white smoke, when revved. Coolant tank looks like chocolate milk. Oil is dark, but dad says it looks like oil, although she just had it changed three weeks ago. No visible leaks, at least what my dad says. I notice it looks kind of wet on the left side of the head/block.

0201: cylinder misfire
0401: insufficient flow

LIMG? Or head gasket? Dad seems to think the latter, however I jump on the LIMG bandwagon.