Electrical problem with 2000 Intrepid
 

For months my car has acted a bit werid. Every now and then the alarm will go off for no reason at all. No one will be near it or nothing loud or vibrating would be near to make it go off as well. For the past two days it keeps going off in 20 minute variables and I have to end up pulling the horn fuse at work since I can't run out every 20 minutes to turn it off. When the car is unlocked the alarm doesn't go off. The alarm is the stock system that only goes off if the car is locked and the door has been opened from the inside or forced opened from the outside. I have asked a few techs at Dodge and they said it would cost about 200 bucks to test the car's wireing system, yet they would be doing the same thing I have done for the tests.

Heres a list of things I have check.
Battery terms
Ground wires have been replaced and tested.
All fuses and relays have been check and tested.
All wires harnesses have been check and tested.

Anything else should I check or should I go ahead and rip out the alarm and install a new aftermarket Viper system?