Have 2003 200 HPDI seems to stumble and miss in the 900 to 1200 rpm range .More noticable when first heading out.Improves after running at higher rpm for a while.All filters changed VST tank recently serviced and all sensors checked with voltmeter and ohmeter were in specs.o2sensor and shuttle also removed and cleaned.Fuel pump pressure at vst tank also in specs.Runs good at mid range and high rpm.the only sensor i didnt check was o2.Afraid to put a torch to it.has anybody experienced a similar problem i am leaning toward a o2 sensor.Figured i ask before spending 275 on o2 sensor.Also use ringfree and gas is fresh since i just replaced tank.Is this a common characteristic of this engine or am i being to fussy.Any help greatly appreciated.THANKS.Still a great motor.