[ryan's camaro]

I have a 2002 Toyota Sequoia SR5.

First off, a bit of background information.
Last week, I changed the air filter using Microgard brand. Two days ago, I refilled my tank with regular 87 unleaded. Regular gasoline is this car's fuel type. Then last night, I went on the freeway and noticed that the car wasn't accelerating as quick as before and hung around 2000 rpm most of the time. Today, I ran the tank low and refilled with some premium 91 octane gasoline.

Is this acceleration lag caused by my Microgard air filter blocking more air flow (which actually has more filtering than my previous one), bad gasoline, or some other major problem like a transmission problem?