Help engine problem

Recently i went on a road trip and i stopped at a
circle k and all of a sudden my engine shuts off
almost like it stalled but everything that had to do
with the cars electrical system stayed on. The first
couple times it started and srove normal but then it
started happen alot like every other block but this
time it was very very alow at accelerating.it has a
loud knocking sound while in idle as well. Any
ideas on what this problem is?