8.1 Hard Starting When Warm

[fireball]

My boss recently bought a second hand 1 ton van with the 8.1 in it and it has an annoying issue of not firing right up when warm,cold is fine starts and idles like it should.Starting it with a warmed up engine consists of having to press the accelerator while turning it over to get it to fire and when it does start it takes a bit for it to settle to a controled idle.We dont have any knowledge of this particular engine or what might be causing this but I can give a bit of background as far as the truck used to be a delivery/courier van and we assume regularly maintained with fluid changes.The engine runs strong,actually hauls ass,and has good oil pressure etc but one thing I did notice the last time using it was that it did not warm up to what I would consider normal on the temp gauge for operating range but I also dont know how hot these engines run.There is no check engine light on but I'm tempted to have it scanned anyway to eliminate the possibility of a stored code.I asked a mechanic friend about a cause and he suggested changing the fuel filter or temp sensor but this sounds like one of those problems that will only be found by changing stuff till its cured.Can anyone offer any help?

[bobcat5544]

What temp does the truck run at?

[fireball]

Well to start with this is a metric gauge as It's a canadian truck and I'm going by what the 5.3 in my pickup runs for temp which is about 95-98*,just below boiling,and the gauge in the 1 ton reads well below that,about half on the gauge.This just seems well below normal and I know the gauge reads higher as we had to bleed the air out of the rad once and the temp was reading quite high until that was done.