If been having this stumbling issue with my truck for a while. When it shifts into O/D it stumbles and it only does it in O/D. I have a dp tuner and it does it in every setting. Most noticeable in stock. Fuel pressure is good, icp is new I changed my Hpop to a 17 because I had a 15. And now it does it even more? I got the code P1211 randomly with my 15. Now when I start it the truck runs for a fewsecs and instantly sounds different and I get the code. It runs more rough with the 17 pump as well, I'm assuming that's because its moving more oil faster and the issue is more noticeable now. Any ideas on what to look for?