check the rubber tube next to the the lower intake manifold gasket, there is probably a hole on the underside of the tube coming directly off the engine. (it is a manufacturer defect)
Bad gas, fouled plug(s), engine out of time, vacuum line leak or clogged.
engine load
You may have a timing belt missing a tooth or two, or a worn out timing belt tensioner.
The engine blows. Usually pistons shoot into the engine. In most cases the engine will have to be replaced.
Lift hood. If engine is missing, there will be a large empty space where the engine used to be.
engine rubber mounts or timin out
For an airplane it vibrates a lot and it needs a super- or turbocharger at high altitudes
How much oil is "missing"?
That all depends on the engine you have and the rear gearing.
A flashing engine light is usually a misfire code. Driving with a flashing light means immediate repair you are damaging your catalytic converters or engine. In answer to your question, NO.
Usually a sighn of bad alternator.
If you drive your truck while there is a miss in the engine. You will notice it lacks power and may back fire.. if continued driving it will eventually just quit running