Chevrolet Trailblazer smoking

I bought a Chevrolet Trailblazer 2.8 LTX 4X4 Auto in 2013. The car was brand new and I drove it with the greatest of pleasure without any problems. Then problems started after the 30 000km service. The car started smoking and losing power as soon as you use more torque on a uphill or when you are towing.<br> <br> I then took it to the dealer that serviced it. After about 10 days they contacted me and said my car was fixed. The problem apparently was a blocked air filter. (Was not changed on 30 000km service). I drove it for a few days and the problem was back. I took it back to the dealer, then apparently they changed some sensors and the injectors. I got it back and drove it till the 45 000km service.<br> <br> After a few days the problem was back, this time my car spend about 3 weeks at the dealer where they did some work on it. I got it back again for a few days and problem reoccurred. It was taken in again. This time it stood for a long time. They changed the injectors again and the diesel pump. I got it back and drove it for a few weeks, once again the problem was back. Then the dealer changed some solenoid valve as there was another Trailblazer at the dealership with the same defect, a