Engine/Transmission (1998.5 - 2002) Runs Ruff

[DGamelin]

One of my customers keeps calling about a problem he is having. He has a 02 6 speed. When the motor is hot it runs good, he pulls big loads so as long as he is loaded and making it work it's fine. When it is empty or real cold out side. It staggers and misses. You can watch the temp gauge on a hill when it's working it's fine. Down hill it cools off and hard to keep running. The thermostat is new. any ideas?



93 250 2wd xc 354 auto 256k

04. 5 3500 cc dully 373 6speed 70k

 

[ThrottleJockey]

Check for codes. Sounds like the ECM is not timing the VP-44 correctly. It should advance a little when it is cold. Could be a bad IAT sensor, too.