Except for a single Harvest Golem you don't have a turn 3 play. You don't want to spend mana on playing secrets, you want the broken Mad Scientist to fetch them for you and use turn 3 to build your board with preferably Tinkertown Technicians and Spider Tanks. If you don't have all of these cards a second Harvest Golem is fine too, you simply
need 3-drops.
Also cut the Flamecannon and some of your 4-drops (1x Polymorph - using these in the midgame gives up too much tempo, 1-2x Water Ele and/or a Flamestrike) for some nice cancerous 1-drops like Cockmaster and Clockwerk Gnome. You may run more controlling lategame than most Mech Mages but you're still need to consistently be able to survive until that point, which Mech decks and -Mage in particular only achieve by spamming the board early.
The Ooze isn't really worth the slot either as Annoytron, Chugga and Water Eles if you decide to keep them destroy weapon classes as is.
I thought you guys said the general rule was don't run 2 scientists if I'm running 3 or fewer secrets. Only do it if I run 4+?
You run two Scientists whenever you're running secrets at all, then mulligan the latter away like Soka said. Their value even with only two Entities is still off the fucking charts.