So this is the story, yesterday I hooked up a white rodgers thermostat (digital 1F90-374 which is now discontinued) it wasn't working properly, we thought we had it figured out, but no luck, woke up to a very cold house. So I hooked up the old one again (honeywell T874D1223) and now it won't work, it keeps running and running so I figured the wiring might be wrong. Out of our wall we have red, yellow, black and green. We can't find any literature regarding black wires. So to shut the furnace of I unhooked everything and this is where we are now.

The furnace is gas, in a mobile home with no ac back of original thermostat says 30v and runs from a standing piolit