Valet 554R Remote Start Alarm

I have had this alarm installed on this vehicle for a few months now on a 1997 Chevy S10 Blazer. It worked fine for a while but know when it remote starts it starts for a few seconds then shuts down. Sometimes it will only crank for a second then shuts down. I have checked all the wires and they seem to be right. It also has started twice by itself without touching the remotes. Any suggestions or comments would be appreciated. Thanks, John

starting by its self sounds like timer mode, if it has that option.  other wise, try reprogramming the tach wire and see what the voltage on the battery reads before and during the operations.  it should be over 12.6vMECP certified installer