went into limp mode ABOUT 1000 mi back while climbing hill . Then it did it again on a smaller grade towing a vehicle. Then slowed again about 100 mi later on a small grade . I changed the fuel filters and tranny filter. Tranny oil nice and clean and no burn smell. Engine does not over heat. check eng light stays on after installing a TS Performance Programmer at about 30000 mi. The installing shop said that is normal because they blocked the EGR. The original owner said he had the same limp mode problem at aboutt 25000 mi and warranty replaced the fuel riser pump which solved the problem. This is a 2006 5.9 cummins with 60000 mi. on a front engine Freight Liner class A motor home. The codes show SPN-411 and SID-251. A local tech diagnosed the first code as becaused by the EGR being blocked and the second being electrical with no connection with the limp mode problem. Sure would appreciate input from anyone that has had this problem and found a solution. diverart@yahoo.com