Pulse Engine Satellite??

Hello,  This sighting happened approximately 6 years ago, while I was working night shift as a machine operator.  I went outside to smoke a cigarette.  I've always been a stargazer, so I've seen moving satellites on a few occasions.  They look like a "slow" moving star.
 This object I witnessed appeared to be a satellite at first, only about double the size and maybe the same altitude as a satellite.  I saw no discernible shape, just a bright light, about the same brilliance as a star or satellite.
 Satellites move on a steady trajectory across the sky, which is why I'm reporting this.  This object moved along steadily at first for about 5-10 seconds, then moved in a way I can only describe as if it had some  sort of pulse engine, it was a rapid acceleration/stop, acceleration/stop...but it was a smooth motion.
 It kept doing this until it disappeared from my line of sight behind a building and I lost it.  I've never seen anything like it before or since.  I took to the internet to see if others have seen anything similar, I've only come across one other person on a forum who has.  This is why I checked the box to be contacted by an investigator, in case there are questions, but also so I can ask if you've  heard of anything like this before.
 Thank you for your time.
-Mark