"Parallax" - Janeway orders "full impulse" towards a system three light years distant. Nothing seems particularly unusual about holding station 20,000 km from a black hole. If by "class four," a stellar black hole is meant, then this requires an acceleration capability on the order of 1-5 trillion m/s2. It is difficult to reconcile this episode with modern scientific knowledge, however.
"The Cloud" - "Captain, the only way we can shut down all thrusters is to vent their deuterium into space. We can't afford to lose all that fuel."
"Prime Factors" - Voyager leaves orbit at 4,000 kph.
"Elogium" - Voyager keeps pace with deep space critters that quickly accelerate to 3,000 km/s. And also uses slow relative speeds in the 100-200 kph range to try and sneak away.
In "The 37s," we see Voyager landing; speed on atmospheric entry is 10,000 kph.
It is perfectly clear from "Alliances," "Innocence," and other episodes that impulse engines and thrusters are separate systems.
"Demon" - Paris says that one week at quarter impulse is all that's left in Voyager's fuel tank. Yet they limp all the way to a planet four light years away.
"Once Upon a Time" - an ion storm is detected closing at 33,000 kph on the Delta Flyer. They are unable to accelerate away in time.
"Fury" - full power thrusters could tear Voyager apart.