running acts like a miss but only at 2000-2700rpm
 

I have a 95 ford f250 7.3 zf5 4x4 290k. when I start it, it blows bluish smoke, then it gets hot it stop that's problem 1. after it warms up runs fine untill you get to 2000 rpm to 2700 rpm, in all gears. it acts likes a misfire, it does it and stops. runs fine, and a little bit later dose it again and again. no CEL lights and its got a new cps and a friend said to unplug the ICP and it dose it at 2500 to 2700 rpms but still dose it but the CEL light is on .................. any help would be nice thanks