1992 Ford F'150
4 Answers
I would start by checking the compression. may have a low cylinder.
As it is shaking, look at the mounts securing the engine to the frame. Make sure none are broken.
Take a sparkplug wire off at a time and see which one do not affect engine shaking, the ones not affecting it are the ones that are missing. When u remove the wire, set it aprox. 1/8"away from plug if u do not get an arc between, it's a spark issue, if u do get a strong blueish arc, then it's fuel, compression or something else but at least u'll narrow it down