2008 Sport Trac 4.6 V8 2WD. I have been trying to fix this problem for a while. Started getting a shutter in the driveline between 40-60 mph when in OD. If you take it out of OD, no shutter. Added trans additive to add more bite and it fixed the problem for a while until the shutter came back. Next changed all coil packs and plugs. No change. Next changed drive shaft (needed new one anyway because of worn u joints) and used a can of cleaner for the intake. Runs a lot better but still have the 40-60 shutter. The trans was checked and all pressures are good. I do not know where to go next on this. Anyone have experience with this problem?