I have a luxaire high efficiency furnace made in 1994 that is getting the error code for the pressure switch being stuck open. I took the rubber hose off to make sure it didn't have any holes or was clogged and then used a paperclip to clean out the connection by the fan, but it is still flashing 3 after I reconnected the hose. Is there anything else that I can try to do to fix the situation on my own or is it something that I NEED to call a professional to come fix?

Previous things that were replaced this year were the ignitor and flame sensor (dont know if that has anything to do with it but thought I would mention it)

Check to see if the vent pipe is clogged or obstructed in any way. Look outside where the vent exits the home, and see if there is any obstruction. It may also be as simple as bad pressure switch, which is fairly cheap and very easy to change out. Or it may be plugged drian system if your furnace is a high efficiency unit. Lots of option here. Try as much as you can, and if all else fails, call in the pros. Good luck and please let me know things work out.