993 is false alarming. Where are the sensors located?
 

Run the vehicle systems on a Porsche tester ("Hammer" or Piwis) to show if there are any problems. The tester can run the alarm system and check operation.

If your '95 is the same as my '97, the motion sensor is in the compartment light above the windshield. Hood and engine compartment switches are in the latch assemblies that also turn on the light. The alarm unit looks for a contact closure. Those sensors have plugs that can be disconnected for testing. Glove compartment and door sensors work the same way. I'm not sure how the radio sensor is configured but there is one. Since all sensors are simple switches, radio unknown, just look at the lights they control. The mechanical switches are an unlikely source of trouble if the lights are working properly. Good luck.

Thom

PS, Running a scan of the electronics is a good idea and may save you a lot of hassle. My alarm started doing the same thing immediately after a smog test. It was suggested to me that a certain combination of ignition switch setting and a possible glitch when the analyzer was plugged into the system may have caused the problem. I haven't had time to get it scanned. Right now it's unlocked in the garage.