Hi everyone, for the last week or so when my truck is cold it lopes for a bit until the coolant temp gets up to about 100 degrees. At idle the rail pressure bounced around from 4.1 to 4.6. I've noticed that at WOT it won't hold full rail pressure either. I changed the fuel filter and had my balance rates tested at a shop. They all tested within spec. It had been in the 40s and 50s in the morning when I start my truck so it's not all that cold outside. Any ideas???