Is there anyway that Transmission Fluid can get into the cylinders?? My
transmission fluid level dropped significantly with no signs at all of leakage.
The other strange thing is that a large puff of smoke was emitted from from the
tail pipe for about 1 minute. The almost as much as if a radiator blows.
Some automatics use a vacuum modulator and that's the only fluid connection to the engine. That's vacuum and a defective modulator would allow fluid to migrate to the engine intake where it would burn in combustion. That's the cause of the puff of smoke emanating from the exhaust.
Check your coolant level and or color. The trans cooler is part of the radiator so when it fails, coolant and transmission fluid will mix.