Rpm drops slightly when pressing gas pedal from stop. Car close to stalling.

Hello, This is common with vacuum leaks. If there is already a good amount of air entering the engine with the throttle closed, opening the throttle (and letting in lots more air) can stall the engine or cause hesitation (which you have described). On 4 cylinder Toyota engines with plastic intake manifolds, it is wise to smoke test the engine paying special attention to the intake manifold gasket. Alternatively, you can spray a little starting fluid around the gasket with the engine running to see if the engine speeds up. If the engine speeds up with starting fluid (use as little as possible) or if smoke comes out of the intake during smoke testing, replace the intake manifold gasket. These are not hard to replace, and there are some great how to videos out there.