I feel the same way, im starting to regret putting any money into my car its always something it seems. This weekend im putting in a new starter! Sometimes I just wish I put my money towards a new car.
Ouch that is brutal.. this is something that would be hard to forgive. At least if he owns up to it then you can go from there... but if he never owns up to it id lose my respect for him and basically tell him you no longer have respect for him.
My SD engine used to have some black smoke in the upper RPMS until I rebuilt the engine now its gone... The more miles I put on the car the worse the black smoke got.
And thats the truth! When I first started my engine I had the distributer backwards and all the gas was burning in the headers which got them glowing red hot..
Pull all your plugs make sure your firing on all 8 . Also make sure your getting full throttle, have someone check your throttle body when you have the gas to the floor.