Truck starts fine rev truck up in neutral pops misses white smoke at 2000rpm. Get it up to operating temps misses pops whitesmoke at 3000rpm. What do you guys think poor fuel delivery? Why when it warms up it doesnt do it till 3000rpm? Any help appreciated.

 

One word, "timing". You don't have enough, that's assuming it's not super cold where you are, if so then it could just preheaters or other engine heat related issues. White smoke is usually unburned fuel.

 

Do not rev the engine above 1,100 rpm when it is cold. Let it warm to operating temp and then never rev it up above 1,200 rpm without a load. Cold reving will trash your pistons, and no-load reving will blow the rod bearings.

For the problem. From your signature, I see nothing about the engine ever having been retimed. All the 94-98 12 valves will slip timing because Cummins failed to torque the nut on the injection pump drive to the proper specification.

If you have a pyrometer installed, take the truck for a drive with a load and if you see your EGT running about 300 degrees higher than what it used to, you will know for sure that your timing has backed down.