2006 Ford Explorer P0106 Fault: Shaking, Poor Acceleration, and Engine Misfire After Gearbox Rebuild

I own a 2006 Ford Explorer with a 4.0L V6 engine and automatic transmission. Two days ago, while driving on the highway, I noticed the vehicle began shaking suddenly after stopping for a short period. The engine felt sluggish, as if the gas was 'sinking,' and a check engine light illuminated. The shaking persists in both drive (D) and neutral (N), with noticeable misfires at higher speeds. I recently had the transmission rebuilt one month ago, and the vehicle has accumulated 345,000 kilometers. Given this history, is the current issue related to the engine or specifically the Manifold Absolute Pressure (MAP) sensor? What steps should I take to diagnose and fix this problem?