I bought my 2001 dodge 5.9 liter 4 wheel drive gas truck NEW it ran great for months. Then the dealer called and said there was a recall on the knock sensor . Well I took in for service , they placed something in fuse panel under the hood next to the battery. It ran great once again. Now when I try to go up a steep grade or try pass someone on the highway it knocks real BAD !!! It does not sound like a lifter or valve ??? Help thank you. I had 2 mechanics look and drive it ! They where not sure what it is ???