Q: What would cause a Ford Ranger to shake when the accelerator is pressed?

It’s either motor mounts or an engine management fault (ignition, fuel, air induction, etc. but also including uneven cylinder compression and mechanical issues) or perhaps a combination of the two. The root cause(s) of the problem can be pinpointed if you request an engine vibration diagnostic. To evaluate motor mounts, you can try shifting from "neutral" to "drive" and back, while the engine is running. If the vibrations disappear or reduce dramatically in "neutral," it’s likely that you need new engine mounts. All other tests will require sophisticated diagnostic tools and hence I encourage you to request the engine vibration diagnostic to get this resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.