1992 Toyota 4 runner alarm issue

[Theshock]

I recently purchased a used 1992 Toyota 4 Runner and I seem to be having issues with the factory alarm system. The damn thing keeps going off for no apparent reason at all. I could be removing groceries and taking them in the house and the alarm will go off, I'm assuming because I left the car door open. If the key is in the ignition, I don't seem to have any problems. I disconnected the alarm under the driver's seat but this prevents me from being able to start the vehicle at all. Does anyone have a suggestion on how to solve this sensitive alram?