My 2001 Hyundai Sonata has a recurring problem. Everytime at 20 mph (when
the car is slowing down on its own), I feel a slight pressure on the
engine that slows the car down even further. This does not feel natural to
the car and started a few months ago. I took the car to Hyundai service and
no trouble codes were found. They acknowledged that the problem exists but
they didn't know what it was, and they sent me on my way. Any ideas what
this may be?

Thank you,
Matt