My truck will cough momentarily, as I'm driving it feels like I lose power momentarily and it throws me forward, then goes back to normal. I asked a mechanic about it, he said to check where the air enters the engine, the valves could have carbon build up on them.
But I'm trying to figure out where exactly those valves would be, and how to get to them. Can anyone point it out from my picture?
If the valve the mechanic was refering to is your throttle valve, then it is in your lower picture by the plenum. Be careful when removing and do not damage any of the hoses, you have a mass air flow sensor upstream and it will not correctly read the air flow into the engine if you damage a hose.
Sounds to me like an ignition miss. Remove the spark plug wires (one at a time) from both ends and inspect for corrosion. Also check for engine oil in the spark plug wells and possible tracking on the plug insulation.