i have set my idle twice in the last 6 months or so... the last time was about a month ago, and already looks to have dropped at least 50-100rpms. the biggest problem i have with that is once it gets below about 700rpm, it doesnt like to start unless the the throttle is bumped just a little.
has anyone delt with something like this? could it be just a worn throttle adjustment screw? or could my pump be having a problem

also it is a 160 pump with about 140k on it

 

The idle adjustment screw does tend to wear from the rattling diesel engine hammering on the contact surfaces.
Of course they only hammer together while idling.
Could it be that you idle a lot possibly in stop and go traffic or excessive warm ups?

 

Don't overlook fuel supply.I have seen issues with bad overflow valves too.

Bob

 

i hope thats all it is... i do warm up about 10-20 min. every mourning, not to much stop and go though, but still seems to be happening wrather quicker than it should... also, i do have good fuel press. and new overflow valve about 5k ago.

 

Does the idle drop consistantly?
What I mean does it drop then sometimes go back up?
If the idle is jumping around on you it could be one of your throttle return springs is broken. There are two of them, one inside the other.
They run from the throttle linkage to near the power steering pump.
With only one it will sometimes also make your throttle touchy.

 

it seems to be slowly droping off consistantly, and doesnt come back up at all, the springs are all intact, im at a loss... the only thing im hoping for is,... on an older ford 7000 that had a 12v in it, i saw that adjustment screw had a good notch wore in to it. maby mine does too, and when i adjust, maby it is just catching the edge of a worn spot and wearing it back down.
maby...just a thought. wish i could get a good look at mine, but due to that wonderfull location....