Yeah, thats exactly what is causing problems with our Pierces, 3 of the 4 engines have had the emissions updates on them, and they are POSs, the 4th didn't have the updates for emissions and is doing OK. They bog down and DON'T move, takes a good 15-20min for them to warm up to actually get going at a good pace. At my house the first guy there turns the truck on and puts it in high idle to warm it up, and it sits for about 5min before we have a full crew ready to roll out the door, yet we cant get out of 3rd gear usually or past 30mph. We've also had the fuel injectors, pump, etc. replaced several times. This works for about a week then starts all over again, we're now slated to get block heaters.
THANK GOD Cat's out. Glad to know Cummins and Detroit are going great, we're up for a new engine probably within the next 2 years.