I have a 1987 f250 with a 6.9 IDI ..The truck is missing out when you first start it up and shakes pretty good.It with run great for awhile when it gets warmed up and then start missing out and then start running good again and some times you with be driveing down the road and its like someone just turns the truck off and then 3 seconds later its on again:bang ...I replaced the fuel filter and the injector o-rings on top of the injectors along with the lines and caps to the injectors ..IM thinking the the injector pump is goin out... :thankyou2: