There's a big developmental leap that starts right about the time you say this started and it tends to make sleep crazy--at least for my kids. All three went from sleeping 6-10 hours straight to waking every 3 hours or more often right around 3.5 months. So the food and sleep might not be quite as linked as you say, except that both problems may be stemming from increased wakefulness.
Two different ideas--
One, try feeding right as LO wakes from sleep--either go in and wake LO or jump in the moment you first hear noises. Keep LO swaddled and the room dark and let it be a very mellow sleepy feed.
Totally different direction, try stripping baby down so you can feed skin to skin. I was just reading some bfing info about how important skin to skin contact can be for good feeding and that sometimes feeding swaddled makes a baby feel sort of disconnected from mum and doesn't foster a good feed. Strip baby down to diaper, get baby latched on nicely pressed up against your skin, then drape a blanket over baby's back to keep him warm.
Also, he may simply have become a more efficient feeder and may be taking more milk and less time.
