Engine Heat in CAB, Slight Power Loss

I had my truck in the shop for severe lack of power and blowing white smoke out the tailpipe upon takeoff, like from a light. Repairs made: Air and Exhaust systems carbon cleaned, air filter cleaned, new EGR Cooler, new EGR Valve, New Turbo, New MAP Sensor. The power is better, but I am still getting a slight lack of power, especially when taking off from a stop. The big problem I have is the engine is throwing a LOT of heat into the cab. The dashboard get hot especially by the light controls, to the left of the radio and climate controls, and under the steering wheel where the fusebox cover is. It feels like the heat is on full blast. I would appreciate any help you can give me. A dealer said it was the oil cooler, but my mechanic says the oil cooler tests didn't show a bad oil cooler. Any ideas?