They'll look for the main culprit- A vacuum line leak, or something mechanical in the engine (Usually you get a check engine
light though). They will look at the transmission system obviously.
If you have time before dropping it off at the shop, I HIGHLY suggest you go to parts store or Wallmart ect. and pick up two cans of "Seafoam" gas treatment. Put one full can in gas tank. Suck the other can up into the upper intake manifold with the engine running
- Open can of Seafoam, put a drinking straw inside, pull out the pcv valve and put the end of the pcv valve to the drinking straw and slowly let it suck up the Seafoam.
The smoke from exhaust pipes is normal and will clear up quickly.
Getting that out of the way will help them diagnose alot easier with alot less second guessing.