Sub Zero cold. I have a 2008 Trailblazer. Drove to work this morning and everything was fine. Left for a docotors appointment about 2 hours later, and on the way the truck would not go over 20 mph. At stop lights, it would idle really rough. I limped to the appointment which last about 1/2 hour. I started the trail blazer up and everything seemed to be back to normal. Does this sound familiar?

SOURCE: Heater blower doesn't work

it sounds like the themostat has stuck open. i would change the themostat and also make sure that there is no debri caught in the grill . make sure the plow is not blocking air flow

SOURCE: 2002 Silverado 3/4T HD 4X4. Started

Yes its possible that fuel pressure is getting low or fuel filter is getting clogged or the O2 sensors are getting hot, O2 sensors when get weak, they get hot and loose communication with cars computer and due to that car stops controlling fuel and this can be problem.Also there are other possibilities like, faulty or dirty, IAC valve or dirty throttle body.Getting all this possibilities inspected, checked will point towards the cause of problem.--------- This should help.Thanks.Helpmech.