2009 250 HPDI Series 2.
First, from what I understand they idle on 4 cyl..... is this correct? if so that explains why it idles rough when not in gear but when in gear is very smooth. Second, I have a hot foot installed and when I try and give it gas (in neutral) it just acts like it keeps running on 4 cyl. and sounds like it is loading up. When I put it in gear it smooths right out and runs fine..... is there just no way too rev it up while not in gear or is something wrong?