Nissan Repair: 1998 altima stock alarm, and engine light, bit of power, random times

Question
I have a problem with my car's stock alarm. The alarm seems to go off on its own at random times. Some days it does not go off and does other days. I was wondering what is the cause and how much it will cost to fix. My second question is about my car's engine light thatis on. I when to go check it out by a mechanic who did the test to find out what was wrong and could not find anything. He resetted the system but the light cam back on. Alos the car seems to be losing a bit of power when it is idle. If you can let me know what might be the casue, that would be great.

Thanks

Answer
Larry,

First, check all the pin switches on the doors as if one is defective it will cause the alarm to go off.  And, this includes the one under the hood.

On the engine code go to Autozone or Checker and they will read the code for free and let you know what it is.  Email me back with the code and we'll discuss.