I have a 99 t reg peugoet 806 1.9td, its burning oil and poor on diesel when you put your foot down clouds of black smoke pours out. The turbo feels like its working fine, but at other times the car has no 'go' in it what so ever. The engine misfires at various revs even when at idle, I've been told this is a start of head gasket trouble.

Hot air comes out of the vents inside the car most of the time even when heater is not on and other times its cold, temp gauge goes up to 90 but then cools down. I had a vacumm switch changed for a second hand one, as the other one was faulty. I don't know what to do as I keep taking it to the garage for repair and it's costing me alot of money.