I have a Frigidaire FG6RK072C-12 furnace for about 7 years. It started to have problems a couple days ago. The motor was running and then ignitor was on. But the burner might on for a short period of time and then cut off or it would start and cut off right away. I got a "pressure switch stuck closed" indication. Even I changed a new pressure switch, I still had the same problem. The system seamed quite sensitive, I just touched any wire, it started a new cycle again. Note that I did try to make sure all connections are properly connected. Could this likely be the control board problems or I should open up the motor to do some clean up/rubrication?

If you touch any wire and it does that the first thing I would check is for a bad or corroded ground connection. check and report back. The ground wire is supposed to be green but can be any color. Loosen wire then retighten.

Thank you hvac1000! Your suggestion was quite good since it triggered me to review all connections of furnace one more time. The ground wire connection was fine. I used a volt-meter to make sure the ~0 ohm. After turned on the power, I touched the white wire from thermostat and ground. I did get ~26ACV and you know what the furnace was running as normal until I took out the measurement. I tried this twice and got the same behavior. So I checked the wires from the thermostat t the control unit. I found the yellow wire a little bit loose so I secure it. It runs now and hopefully it will stay this way.

Good deal glad you got it fixed.