My dad's 2004 6.0 4x4 250 began to lose power, it missed a few times then died. It set a p2290 code. We cleared it unhooked the batteries waited a little then cranked and cranked till it finaaly started very slowly. It would idle just fine but would not rev up. Unplugged the icp but didnt change anything. Checked the oil level also fuel supply and everything seems to be kosher. any thoughts????