Ok, so I'm way behind on this, so I should get right to the results...
For round three, you have chosen S4 - The Lost Cavern of Tsojcanth as your favorite old school module with a hefty 33% of the votes
In second place with 18% was B3 - Palace of the Silver Princess
3rd place was a try between the surprising underachiever D1-12 - Dragonlance Saga and I1 - Dwellers of the Forbidden City
4th place was held by N1 - Against the Cult of the Reptile God
For 5th place we have our first ever three way tie between H1-4 - Bloodstone, UK1 - Beyond the Crystal Cave and WG5 - Mordenkainen's Fantastic Adventure each with 3%
and in last place, sadly with 0.0% is EX1-2 - Wonderland Adventures. Clearly this was not one of TSR's more popular adventure concepts.
Be sure to vote in the Final Round of Favorite Old School Module to determine who the ultimate winner will be.