Intermitten white smoke from the tailpipe, does not occur all the time but once in a while a large cloud of white smoke

I’ve had vehicles come in with white smoke to me it might be vapor that’s due to water going thru the pistons.

I have had the same prob in my 1996 Lumina. Thought it was rings or valves. Check out your trans vacuum modulator to see if the gasket in it is bad. If so, then it is sucking trans fluid through the vacumm hose back into the intake manifold and burns it in the chamber. Mimics a valve or ring prob. Also check the PCV hose and connections. It could look fine, but it does not take much for a bad hose/connection to foul the PCV function. It will blow smoke out the tailpipe too.