I have a question about a 99' drw ford f-350 psd. It has what feels like a miss right above idle, but it smooths out what seems to be about 1,000rpm. The truck has a aftermarket exhaust system, and a bullydog chip. Other than this it seems to run fine. also want to add the truck is a standard shift. Read all of the treads I could find but none seems to match this problem exactly. Your help on this would be greatly apprectiated.