I have an electical sound or knock like when welding and you get the arc of steel sounds like a sizzle almost how truck sounds. Started a while back only going up hills when engine needed gas when hit gas or let off it quit. Now it does it on any slight grade. 2005 fx4 5.4 all plugs done at 96000 truck has 105000 noise started about 98000. No codes come up had it to 2 dealerships cant figure it out. Any suggestions