recently have noticed that whenever I step off the gas pedal, there seems to be some sort of resistance and the speed drops off much faster than usual. this only happens occasionally and not at all times, but seems quite odd. as if I was v. slightly braking, but I am not. The RPM is generally above 1K when this happens, whereas for smooth rolling, I believe it is 0.5K RPM? But I am not sure if this has anything to do with it. i drive auto trans.the feeling is comparable to when driving manual and letting the engine break by shifting down one gear when approaching a stop.Usually I could roll for a long time when I reach like 30 mph and now I can see and feel how the speed drops off much quicker it doesnt feel nice at all. What could be the problem here?