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Message: [QUOTE="Marty, post: 1069645, member: 602"] Well I have a truck here in the shop and I have not experienced this issue before and I can not for the life of me figure it out. I am hoping someone on here can give me some place to turn. Here is the story: Truck went to another shop before coming here for the same problem. ISSUE: Truck rpm oscillates @ idle. Almost sounds like it is going to die at times. Unplug the ICP sensor and it idles perfect, but with 1280 code obviously. The oscillation started while the customer owned the vehicle. It was not there prior to purchase. It has over 211k miles. Oil level is perfect. Previous mechanic, replaced trans selector switch, did ICP sensor and pigtail and then also did TPS sensor. Issue still there, so mechanic unplugged ICP sensor and told the customer his diablo sport programmer wouldn't clear off his PCM. Then he told him his PCM was bad and sent him on his way. Wellllll... despite the fact I didn't think the PCM was the problem, I swapped it with another PMT1 DPC 422 out of an identical truck. No change. I checked the resistance at the ICP sensor plug. All were in spec according to fordinstallersupport.com. I also put another ICP sensor in from FORD just to be sure. Swapped in a brand new test IPR. No change, I replaced the pigtail on the IPR because it had **** caked inside of it. No change. I checked continuity from PCM to the 42 pin and the ICP/IPR. They were all <1. I swapped HPOP's, still does it. I pressurized each head individually. Both held pressure. Oil looks fine running. Fuel pressure idle 60. Fuel quality good. F250 so no deliminated tanks like in 450/550 trucks. Icp v is going from 0.66-1.30 @ idle. Psi readings are 453-637. Ipr says 12-13% Rpm 630-713 Very noticeable at idle. Accelerator pedal pos voltage idle .61v wot 3.93 It does it in ANY gear selection. Park, Reverse, Drive, 2nd, 1st as long as it's idling. The customer has also stated that the truck has been shutting off recently now. Never did before. To recap, ICP sensor Replaced, IPR replaced, HPOP swapped, Heads Pressure Checked, truck idles perfect without the ICP plugged in. All wiring checked for continuity that concerns the ICP, IPR from the sensor to the PCM. Resistance check also in spec. [/QUOTE]