Complete 2 system furnace repair and preventative maintenance check. Find downstairs furnace 23-year-old operating with rusted inducer connector and need to keep a check. Find the pressure sensors worn and need to keep a check. Gas line not up to code. Replace 20x25x5 filter. Find upstairs in poor conditions due to worn motor, inducer assembly worn. Ignition miss fire and CO Level over 4000 ppm. No safe to operate. Shut off the system, need to replace the system.