Pretty much exactly what the title is. It only happens after I drive on the interstate for a while. 2 hours or so. When I get off i will have a rough idle and almost no low end torque. I have to keep it at around 1500 rpm and slip the clutch until I get going. After I get going about 5mph I can let the clutch catch and it will run fine through every gear change. So far it will go away and gain the torque back if I let it sit for a little while. Anyone have any ideas? The only code being thrown is P 0551.