Hello I'm new and I need help. I have a 2000 cummins. The truck idles fine and when I put it in any gear other than reverse it stalls out almost immediately. I talked to the guys at ATS because the previous owner put their stage one trans in the truck and they said it could be the valve body. I'm wondering if any one else was having this problem and if they knew what it was and the truck was throwing a p0237 code. I replaced the map sensor and that didn't do it. Then I replaced my batteries because they wer bad and nothing helped. If someone could help me out it would be greatly appreciated.

 

Code p0237