Rythmic Vibe in the Gas Pedal

Hi all. I have an 2010 access cab 4x4 v6 speed with 7000 miles.

I took it out today and it has developed an engine vibration thru the gas pedal. I was sitting at a stop light and started to feel it pulse every couple seconds in the brake pedal just like the gas pedal. I can rev it to any rpm and the pulsing vibe is there in the gas pedal (in and out every couple seconds), clutch in or out doesnt matter. It doesnt get stronger with higher revs either which is wierd. It never changes intensity or pattern..just in and out every 2 seconds.. Driving makes no difference on how it feels versus being sitting still..

The only thing different recently is went from 93 octane to 89. Could it be an internal motor issue? Or Maybe a pulley?