what are the symptoms of slipping out of time. my the truck will flutter on smashing the pedal to the floor and holding at 3k rpm it will emit blue and a little balck smoke. it seems to loose power above 1900 rpm just revs. once in over drive it takes a lot to get up to speed due to rpm drop cause it wont accelerate much more than 45mph, note this is loaded (trailer) let up on pedal and it will shift into od and then will roll down the hwy real well. my egt gauge is broke (will be getting a new one). when under load it does not do flutter or spudder. the truck has 260k on it, no diesel in oil or other problems the transmission is fine its a Goereand. any ideas or info thank you.

 

I would first verify my fuel pressures. Usually when the timing slips it slips big.

 

I am thinking the over flow valve [OFV] is shot, and not letting the lift pump build enough pressure.
I second checking the fuel pressure to the injection pump.