Truck makes a "rop rop rop sound" when started.

[polarisrider4life]

It doesn't bother me and it doesn't seem to hurt the truck, but does anyone know why my 97 7.3 sometimes makes a rop rop rop sound with the idle when started sometimes? It goes rop rop rop once the motor catches and then the idle increases slowly from bout 300rpm to the 600rpm for idling. When i change my oil i always replace the fuel filter and for like 3 weeks after the fuel filter change it doesn't usually do it, but i have just always wondered why it does that. thanks guys!

[Dietoremain]

could be a few things.. most likely your GPR or glow plugs need replacing, when a few or more stop working it becomes more noticeable in the cold.. you think thats bad you should hear a 6.0 with a bad FICM start... thats fun.