krcarr 
2008 Nissan Pathfinder SUV SE 4dr SUV (4.0L 6cyl 5A)
2008 Pathfinder SE - transmission issue
 I have been experiencing the same issue of bucking/thumping at or around 40mph. When lightly pressing the gas pedal the vehicle shakes or shudders but only around that speed.  A senior tech witnessed the problem and said NIssan is working on it , but it had to get cleared by EPA.  Not happy with this 08. Very disappointed in Nissan.