Took my truck in today for a reflash because I thought it was what it needed. Turns out it dose not hold its fuel pressure when I shut it off. So dealer thinks there is something wrong with the return lines or something.I had to make another apointment next week. Is there anything I could check to see if I could solve the problem? No more warranty so it would rely help if I could figure it out........

 

Also it dose not idle down smooth,almost like it surges when idleing down. And it has slow starts, about 5 seconds of cranking till fuel pressure builds up then it starts....