Trucks going into the shop again

So I've posted on here a few times about my truck. It is an 09 F 250 and it has been in the shop over 6 times in the past 4 months for the same issue. I was having issues with it blowing white smoke and it continued to go into the regen cycle. The last time it was in there they replaced an injector and the DPF sensor. Well I have had it back for close to a month and now I'm having the same issues plus it is idling very rough and feels under powered The truck has right under 30,000 miles and at this point I'm getting a little frustrated with the truck being in the shop almost every other month. Any suggestions on what to do or what to say to the dealer this time?

Chris