i just got my motor rebuilt and it idles up and down between 500 and 1500 rpm im not sure if its normal it also sometimes stals at red lights and at night when i have my head lights on it dies more often could this be an electrical problem it really starting to get annoying someone please help!

 

I with say start from the basic check your battary, battary cable, alternator, and tps

 

What is your vacuum reading when the idle is around 800 rpms?